Dear brothers, it was narrated through a number of chains of narration from Anas and others, stating that the Prophet PBUH climbed up on the Minbar, and then said, "Ameen, Ameen, Ameen." It was said, "O Messenger of Allah, why did you say Ameen?" He PBUH replied:

(Jibril came to me [Pay attention to this Important Hadith] and said, "O Muhammad, he is doomed who hears you mentioned and does not say Salla upon you.'' He said, "Say Ameen,'' so I said Ameen. Then he said, "He is doomed who sees the month of Ramadan come and go, and he has not been forgiven.'' He said, "Say Ameen,'' so I said Ameen…) 

When does man expect to be forgiven if not in the month of Ramadan?!

Ramadan is the month of repentance, Siyaam (fasting), Taraweeh and offering Fajr in the Masjid.

(He is doomed who sees the month of Ramadan come and go, and he has not been forgiven.'' He said, "Say Ameen,'' so I said Ameen…) 

When does man expect to have his sins forgiven if not in the month of Ramadan?!