The greatest pillar of Pilgrimage is standing on the mountain of Arafat, as the Prophet (PBUH) said:

“Hajj is Arafa”

 Therefore, the day of Arafa is considered the day of the greatest encounter between a repentant slave and his Forgiving and Merciful Lord. It is the day of knowledge and the day of forgiveness. On this day, Divine Mercies are showered from Allah, the Creator of the earth and the heavens upon His servants. That is why it has been said that whosoever stands on the mountain of Arafat but does not feel certain that Allah has forgiven him his sins and misdeeds, his Pilgrimage is not accomplished.

 Jaber (May Allah be pleased with him) narrated that the Prophet (PBUH) said:

“There are no days better with Allah than the ten days of Dhul-Hijja.” A man asked: “Are they better than ten days of Jihad for the sake of Allah?” He (PBUH) said: “They are better than ten days of Jihad for the sake of Allah. And there is no day better with Allah than the day of Arafa, (on which) Allah, the Almighty, descends to the lowest heaven and boasts of the people of the earth to the inhabitants of the heavens. He says: ‘Behold My slaves! They have come unto Me unkempt, dusty, and struck by the sun’s rays. They have come all the way seeking My Mercy although they have not seen My Punishment!’ There is no other day on which people are emancipated from the Fire more than the day of Arafa.”

[Al-Muntheri said: it was narrated by Al-bazzar, Ibn Khuzaima, and Ibn Hibban]

 Ibn Al-Mubarak narrated from Sufyan Ath-Thawri on authority of Az-Zubair Ibn ‘Ali that Anas Ibn Malik (May Allah be pleased with him) said:

The Prophet (PBUH) stood on (the mountain of) Arafa, when the sun was about to set, saying: “O Bilal! Let people listen to me!” So Bilal stood up and called out: “Listen to the Messenger of Allah (PBUH)!” So people listened. The Prophet (PBUH) said: “O people! Gabriel has already come to me, and he delivered me my Lord’s Salam (Greeting). Then he said: ‘Allah, the Almighty, has forgiven the people of Arafa and the people of the Sacrosanct Place.’” Then, Omar Ibn Al-Khattab stood and said: “O Messenger of Allah! Is that only for us?” He (PBUH) said: “This is for you and for those who will come after you until the Day of Judgment.” So Omar exclaimed: “How Great and Abounding Allah’s Favors are!”

  Imam Muslim and sh3er narrated on authority of ‘A’isha (May Allah be pleased with her) that the Prophet (PBUH) said:

“There is no day on which Allah emancipates a slave (of His) from the Fire more than the day of Arafa. And Allah, the Almighty, truly comes near and boasts of them to the Angels, saying: ‘What do those (slaves) want?’”

 Abu-d-Darda’ narrated that the Prophet (PBUH) said:

“Satan is never seen pettier, more defeated, or more furious on any day than that of Arafa. This is because he sees the sending down of (Allah’s) Mercy and His Forgiveness of great sins, except for that which he was made to see on the day of Badr.” They asked: “What did he see on the day of Badr?” He (PBUH) said: “He saw Gabriel leading the Angels (in support of believers in the fight against the infidels).”

[Imam Malik and Al-Hakem]

  Imam Ahmad And At-Termidhi narrated that the Prophet (PBUH) said:

“The best supplication is the supplication of the day of Arafa; and the best thing that the previous Prophets and I have ever said is: ‘There is no god but Allah, Alone, with no partner; all Sovereignty belongs to Him; all Praise is to Him; and He has power over all things.”

 It was narrated that Housain Al-Marwazi said: “I asked Soufian Ibn ‘Uyaina about the best supplication on the day of Arafa. He said: ‘There is no god but Allah, Alone, with no partner.’ Then I said: ‘This is a kind of praise and not supplication.’ He said: ‘Don’t you know the Hadith narrated by Malik Ibn Al-Harith? Such is its explanation.’ I said: ‘Tell me about it.’ He said: ‘Malik Ibn Al-Harith narrated that Allah, All-Mighty, says:

‘If My slave is preoccupied by extolling My Praises over beseeching Me, I give him better than that which I give to beseechers.’

 He said: ‘Such is the interpretation of the Prophet’s Haith.’ Then Soufian said: ‘Don’t you know what Umayya Ibn Abi-s-Salt said when he came to Abdullah Ibn Jad’an asking him for a donation?’ I said: No!’ He said: ‘Umayya said:

Shall I mention my need, or your modesty is sufficient for me?
For your nature is modesty;
And your knowledge of rights and you are a good man,
Honor and praise are both yours;
If one should praise you one day,
It is sufficient for him to be granted honor by praising you.’

 Then he said: ‘O Housain! Such is a creature; and it is sufficient to praise him instead of beseeching him. So what do you think of the Creator?!”
 The story of the Prophet Yunus (Jonah), (PBUH), best confirms this meaning, for there is no disaster that is more grievous than that when one suddenly finds oneself in the darkness of a whale’s belly, in the darkness of the depth of the sea, and in the darkness of the night. There is no disaster more catastrophic and hopeless than this one. Yet Jonah (Yunus) (PBUH) called out to the Lord, All-Mighty, Most Merciful:

﴾But he cried through the darkness (saying): La ilahailla Anta [none has the right to be worshipped but You (O Allah)], Glorified (and Exalted) are You [above all that (evil) they associate with You]. Truly, I have been of the wrong-doers."(87)So We answered his call, and delivered him from the distress. And thus We do deliver the believers (who believe in the Oneness of Allah, abstain from evil and work righteousness).(88)﴿

[Al-Anbiya,87-88]

 Contemplate Allah’s Words
  “So We answered him”, which means that Allah considered Jonah’s praise of Him as a supplication, and, therefore, He said: “So We answered him, and delivered him from distress”.
Even more, in order that readers of the Noble Quran do not think that this story is a non-repeated historical one that would never happen again, Allah, Most Merciful, made it as a Divine Law that applies to all places and times, saying:

﴾ And thus We do deliver the believers (who believe in the Oneness of Allah, abstain from evil and work righteousness).(88)﴿