(V.48:2) Narrated Al-Mughîrah: The Prophet صلى الله عليه وسلم used to offer night prayers till his feet became swollen. Somebody said to him, "Allah has forgiven you your sins of the past and the future." On that, He said, " Shouldn‘t I be a thankful slave of Allah?" (Sahih Al-Bukhari, Vol.6, Hadîth No.360).