There is a contract of faith between the believer and Allah:

Brother, this is our 8th lecture of "Al Maïda" Chapter, verse 6. Allah the Almighty has said:

﴾O you who believe! When you rise up to prayer, wash your faces and your hands as far as the elbows, and wipe your heads, and your feet to the ankles; and if you are under an obligation to perform a total ablution, then wash (yourselves) and if you are sick or on a journey, or one of you come from the privy, or you have touched the women, and you cannot find water, betake yourselves to pure earth and wipe your faces and your hands therewith, Allah does not desire to put on you any difficulty, but He wishes to purify you and that He may complete His favor on you, so that you may be thankful.﴿

[Al Maïda – 6]

Brother,
About 300 million people suffer nowadays from the so called "filth diseases". However, the Muslim world faces these diseases with a green belt called the ablution and thorough washing. Allah Almighty says:

﴾O you who believe!﴿

and each believer, who listens to this verse, must be certain that he is meant by this speech due to the contract of faith he has with Allah Almighty which consists in believing in Allah, in His Books, Angels, Prophets and Messengers, and in the Last Day; and in believing that fate, either good or bad, is a pure act of Allah. This faith allows the believer to start receiving Allah's orders and commandments.

Mind is used to know Allah and believe in Him

Humans use their brains to get to know Allah and to believe. With this goal achieved, the believer starts to receive. Therefore, each and every verse that starts with[O you who believe!]is addressed to those who believed in Allah's existence, oneness, perfection, knowledge, mercy and wisdom. O you, who were created to live in Heaven eternally, do this![O you who believe!]Hearing this verse a believer feels that each cell in his body and each drop of his blood is meant by this speech:[O you who believe! When you rise up to prayer], which means "if you want to pray". The same applies to this verse:

﴾So when you reauthor the Quran, seek refuge with Allah from the accursed Shaitan﴿

[An Nahl – 98]

Prayer is a meeting with Allah so one should be clean and elegant

If you want to read the Quran,[seek refuge with Allah from the accursed Shaitan]. If you want to pray, do this and this. Here is the rule: everything that is an ordinance cannot be performed without it being an ordinance in and of itself. Therefore, ablution is an ordinance because the prayer cannot be performed without it. And everything a duty cannot be performed without is a duty in itself, and everything that is a sunnah cannot be performed without it being a sunnah in and of itself.

[O you who believe! When you rise up to prayer]because a prayer is an encounter with Allah, one must be pure, clean and even embellished. Allah Almighty says in one guiding verse:

﴾O children of Adam! Attend to your embellishments at every time of prayer﴿

[Al Aaraf – 31]

One should do ablution:

Besides purity, hygiene, wearing perfume and putting on ornaments, one must bring along a good deed to this encounter with Allah.

[O you who believe! When you rise up to prayer]There are some details that should be mentioned. A group of scholars said this is a generic term for every time one is up to pray. First of all, one should perform the ablution, whether they are clean or not. This is how one must interpret this verse.
According to Ibn Sereen, the Prophet's companions performed the ablution for every prayer. While some scholars said this speech is addressed to the Prophet, peace be upon him, sh3er said one should perform ablution for each prayer if one seeks the favor. This is a matter of preference not an obligation. It is preferable that one perform ablution for each prayer. I am reporting here the different views of scholars.
Being the legislator, the Prophet, peace be upon him, did that till the day he entered Mecca and performed the five prayers with one ablution as a sign of mercy. Therefore, we may follow the Prophet's sunnah or perform an ablution for each prayer to obtain more favor.
Other scholars said one must definitely perform ablution when they wake up to pray. In other words, if you want to pray after you get up from sleep, you must perform ablution, exactly like when Allah says:[So when you reauthor the Quran, seek refuge with Allah from the accursed Shaitan]which means "if you want to reauthor the Quran".
According to the sunnah, one may perform several prayers with one ablution, but if one seeks more favor, they may perform an ablution for each prayer. In summer days, when the weather is hot and the water is abundant, there is no harm to perform ablution even when one is clean. But if the weather is cold or an ablution happens to be hard, one may perform several prayers with one ablution. Therefore, one is free to follow the sunnah or to seek more favor.

Allah mentions four parts of the body in ablution:

Another point:[wash your faces]. Allah mentions four parts of the body when performing an ablution: the face that must be washed up to the ears lobes and from the hairline to the chin. The face must be washed over and over and over until it is clean. This is how the Prophet, peace be upon him, understood Allah's order:[wash]means to wash the face first then to rub it thoroughly the second time, and finally to wash it in order to remove the water that has been used in rubbing it[wash your faces]. But before washing their face, one must wash their hands first. This is how the Prophet, peace be upon him, understood the order of the different steps of ablution. Now, is the water fit to perform an ablution? A man who converted to Islam in Egypt spent about six months learning only the jurisprudence related to water provisions until he was about to quit. He then met a wise scholar who simply advised him to perform ablution with any water that is fit for drinking.
Do not perform ablution with any water that you cannot put in your mouth or cannot smell. The mouth and nose rinsing aims for disinfection and clean the mouth from what is left of food, and the nose from the remains of breathing. Therefore do not use the water that you cannot put in your mouth or nose to perform ablution.
The scholars agreed that the face and hands must be washed and the head must be wiped[and wipe your heads], but their views differed about the feet washing. The Quran mentioned these four parts only which are the duties of ablution, and the other details are either sunnah, manners or desirable choices.

Scholars agree that ablution needs an intention:

Brother,
The majority of scholars said that an ablution needs an intention. The Prophet, peace is upon him, said: "Actions are but by intention."[Al Boukhari quoting Omar Ibnul Khattab]Others interpreted the word "manners" in Allah's saying:

﴾Say: Every one acts according to his manner﴿

[Al Israa – 84]

by "intentions". The value of a deed depends on the intention. Therefore, an ablution needs an intention according to the majority of scholars, and the Prophet, peace is upon him, said:

((Actions are but by intention.))

[agreed upon, narrated by Omar bin Al-Khattab]

The intention is the origin of every action. For example, we throw a golden coin on the road, and place a photographer at a distance. A man comes, picks up the coin, puts it in his pocket and wends his way. We replace the golden coin. Another man comes, picks up the coin and puts it in his pocket. Both photos are identical, but the intentions were different. This first man took the golden coin with the intention to look for its owner, while the second man took the golden coin with the intention to keep it for himself. The action is the same in both pictures. However, the first man transcended and the second one fell.

Ablution is not an act of worship intended for itself:

Other scholars said ablution does not need an intention because a worship, that is not intended for its own sake, does not need an intention, and an ablution is not intended for its own sake. One does not perform ablution and say: "Thanks God, I did what I am asked to do." A prayer must follow the ablution. Therefore ablution is intended only as a means to perform a great worship which is the prayer.
Imam al Shafei and his follower, Abu Hanifah, said that the worship that is not intended for its own sake does not need an intention; the intention is obligatory for the worship itself.
Thus, ablution is a condition for the validity of prayer. For example, is magnifying Allah (by saying Allahu Akbar) a condition or a part of a prayer? When a part is performed, one moves to the next part. Standing, bowing, and prostration are all parts of a prayer, while a condition lasts as long as one prays. Facing the Qiblah and keeping one’s self purity must last during the prayer. Some scholars said magnifying Allah is a condition because one must evoke Allah's greatness along with the prayer, while sh3er consider it as a part of the prayer itself. The purpose of magnifying Allah is to always remember that the prayer is a great action; it is greater than closing accounts or meeting X or Y. One leaves the whole world to be with Allah.

The Prophet poured water over his elbows in ablution:

[O you who believe! When you rise up to prayer, wash your faces and your hands as far as the elbows]

The elbow has to be washed as well. Some scholars said it does not, while sh3er said if what is after the elbow is from the same nature of what is before the elbow, the elbow must be washed as well. What is before the elbow consists of skin, muscles and flesh. The same applies to what is after the elbow. Thus, the elbow must be washed as well. The Prophet, peace is upon him, washed his elbows while performing ablution. Jaber said:

((When performing ablution, the prophet, peace be upon him, pours water over his elbows.))

[ the small collector narrated by Jaber]

Judge Abu Muhammad was the only one to clear up the confusion when he said that "as far as the elbow" is the limit for what is left from the arms not what washed thereof. Thus the elbows are included.
[and wipe your heads]: Scholars said the hands must closely touch the head while wiping it. This is what they deduced from the interpretation of the verse:

﴾and be good to the parents ﴿

[An Nisaa – 36]

Which means that one must be in close relation with his parents and do good deeds to them by himself, not to charge anyone else to do it on his behalf.
There are amazing directives and values in the Quran:
There are some amazing deductions. Scholars said about Allah's saying:

﴾and a wave intervened between them, so he was of the drowned.﴿

[Hud – 43]

when Allah wanted to drown Noah's son, who refused to believe in Allah Almighty and to go aboard the Ark when Noah said to him:

﴾O my son! Embark with us and be not with the unbelievers. * He said: I will betake myself for refuge to a mountain that shall protect me from the water.﴿

[Hud – 42-43]

He made a wave intervene between Noah and his son as a sign of His absolute mercy. If we respect and follow the Quran manners and ethics, we will definitely be in a totally different situation.
A plane carrying 27 top scientists, who have been trained to manipulate sophisticated weapons, was shut down. Allah Almighty says:

﴾And he said: O my sons! do not (all) enter by one gate and enter by different gates﴿

[Yusuf – 67]

If one reads the Quran carefully, they will come across such unbelievable guidance and manners.

Accuracy of language is great in the Quran:

[and wipe your heads]: Since the face is a part of the head, should it be wiped as well? A separate verse summarized face washing. Wiping the head means wiping the hair closely with the wet hands, and wiping the quarter of the head is acceptable.[and your feet]: This phrase is linked to the hands not to the head. That is why they should be washed not wiped. The Arabic language is very accurate. For example, Allah almighty says:

﴾and made the word of those who disbelieved the lowest, while the word of Allah – that is the highest﴿

[At Tawba – 40]

If one links[while the word of Allah – that is the highest]to the precedent phrase, the meaning will be as if the word of Allah was the lowest and then became the highest.[while the word of Allah – that is the highest](always) is a new resuming phrase.

The obligation is to wash feet not wipe on them:

[and your feet]means wash your feet. The order, all scholars said, is to wash the feet, not to wipe them. That is what the Prophet himself did. When he once saw some people wiping their feet while performing ablution, he loudly said: "Woe to the heels from the fire."[Agreed on, quoting Abdullah Ibnu Amr]

Ways and cases of dry ablution:

[and if you are under an obligation to perform a total ablution(Ghusl), then wash yourselves]with water of course. This order is addressed to the one who has water at his disposal. If you live in a house where water is available, you must wash your self if you are under an obligation to perform ablution. Per contra, he who is under an obligation to perform ablution and does not have water, or is sick and using water would hurt him, or on a journey where water is missing, or comes from a low place after relieving himself, or has touched women (an euphemism for sexual intercourse), and finds no water, he can betake himself to pure earth by hitting it with his bare hands and wiping his face and elbows.

[and you cannot find water, betake yourselves to pure earth and wipe your faces and your hands therewith, Allah does not desire to put on you any difficulty, but He wishes to purify you and that He may complete His favor on you, so that you may be thankful.]

You can perform dry ablution if water may hurt you:

Here is, brother, an incident that occurred in the time of the prophet, peace be upon him, and quoted by Jaber, may Allah be pleased with him:

((We were travelling when one of us was hit by a stone in the head and got seriously wounded. He then had a wet dream and asked his companions if there is any permit that allows him to betake himself to pure earth. They said there is no permit as long as water is available, and that he must wash himself. He washed himself and he died. We came to the Prophet, peace is upon him, and reported the incident. He said: they killed him, may Allah kill them! Why did they not ask if they do not know? The cure of an illness is but by asking. He could have betook himself to pure earth, or wrapped his wound and washed the rest of his body.))

[Abu-Dawood, narrated by Jaber]

One must not rush to give legal opinions:

One must not rush an advisory opinion or legal ruling. One must ask if one does not know.

﴾so ask the followers of the Reminder if you do not know﴿

[An Nahl – 43]

Either his wound was seriously severe, or the weather was too cold that his wound got infected when he washed himself. The prophet said: "they killed him, may Allah kill them! Why they did not ask if they do not know? The cure of an illness is but by asking."
If one is positively sure about the legal ruling, he may speak up. Otherwise[ask the followers of the Reminder], who are the people of the Quran and the Sunnah,[if you do not know].
Those who overburden themselves are not right. The prophet was fighting in one day of Ramadan. The weather was too hot that he grabbed a pot, raised it high in front of all his companions and broke his fast. But when he knew that some of his companions did not break their fast, he said: "Those are the disobedient." Omar's son said: the Messenger of Allah, peace be upon him, said:

((Allah loves that people profit from his permissions as much as he hates to be disobeyed.))

[Abu Daoud]

Do not be obstinate or tought:

Do not be obstinate. Do not be tough. Do not overbid the Messenger of Allah. The prophet broke his fast and drunk, and when he heard that some of his companions did not do the same, he said "Those are the disobedient."
But, again, the prophet broke the fast but did not raise the pot. Some of his old aged companions stopped fasting, but the youngsters did not. When the iftar time came (sunset), those who broke their fast prepared the food for their fellow fasters. The Prophet said about them: "Those who stopped fasting have taken all the reward."
He was invited once with one of his companion to a feast. When food was served, his companion said: "I am fasting, O messenger of Allah!" The prophet said: "Your brother invited you and paid to prepare food for you, and you say "I am fasting"! Break your fast and fast another day."
Some people overbid the Prophet, peace be upon him, but

((Allah loves that people profit from his permissions as much as he hates to be disobeyed.))

Shortening the prayer while travelling is imperative in some doctrines like the Hanafiyah, as Allah wants you to reduce the number of prostrations while travelling by two for both the noon and the afternoon prayers. If Allah allows you to shorten the prayer, you must shorten it, but when He orders you to complete it, you must obey.
That was, brother, the verse of ablution.

﴾O you who believe! when you rise up to prayer, wash your faces and your hands as far as the elbows, and wipe your heads and your feet to the ankles; and if you are under an obligation to perform a total ablution, then wash (yourselves) and if you are sick or on a journey, or one of you come from the privy, or you have touched the women, and you cannot find water, betake yourselves to pure earth and wipe your faces and your hands therewith, Allah does not desire to put on you any difficulty, but He wishes to purify you and that He may complete His favor on you, so that you may be thankful.﴿

[Al Maïda – 6]