سنن ابن ماجه

It was narrated from Ziyad bin ‘Ilaqah that he heard Mughirah say: “The Messenger of Allah (ﷺ) stood (in prayer) until his feet became swollen. It was said: ‘O Messenger of Allah, Allah has forgiven you your past and future sins.’ He said: ‘Should I not be a thankful slave?’”