‏الصلاة : Hadeeth No:813 Abu Huraira reported: The Messenger of Allaah (sallAllaahu alayhi wa sallam) said: When anyone amongst you utters Amin in prayer and the angels in the sky also utter Amin, and this (utterance of the one) synchronises with (that of) the other, all his previous sins are pardoned....

‏الأضاحي : Hadeeth No:4820 This hadith has been narrated on the authority of al-Aswad b. Qais with the same chain of transmitters....