Bismillah Walhamdulillah Was Salaatu Was Salaam ‘ala Rasulillah Narrated Abu Huraira (Radi-Allahu ‘anhu):
The
Prophet (Sallallahu ‘Alaihi Wa Sallam) said, “Angels keep on descending
from and ascending to the Heaven in turn, some at night and some by
daytime, and all of them assemble together at the time of the Fajr and
‘Asr prayers. Then those who have stayed with you over-night, ascend
unto Allah Who asks them, and He knows the answer better than they, “How
have you left My slaves?” They reply, “We have left them praying as we
found them praying.” If anyone of you says “Amin” (during the Prayer at
the end of the recitation of Surat-al-Faitiha), and the angels in Heaven
say the same, and the two sayings coincide, all his past sins will be
forgiven.“
Bukhari Vol. 4 : No. 446