Book 43, Hadith 36

It was narrated that Anas said:"The Messenger of Allah said on the Day of Sacrifice:' Whoever slaughtered his sacrifice before the prayer, let him repeat it.' A man stood up and said: 'O Messenger of Allah, this is a day when people want to eat meat.' He mentioned that his neighbors were poor and it was as if the Messenger of Allah believed him. He said: 'I have a Jadh'ah that is dearer to me than tow sheep for meat.; So he granted him a concession (allowing him to sacrifice it) but I do not know whether it applied to anyone else or not. Then he went toward two rams and sacrificed them." (Sahih)