Sayyiduna Abu Juhayfah (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) would pray (long voluntary prayers at night) until his feet became swollen. It was said: "O Messenger of Allah! Has Allah Almighty not forgiven your past and future sins?" The Prophet (peace and blessings be upon him) said: Should I not be a grateful servant?
Al-Tabarani recorded it in al-Mu'jam al-Kabir. Its chain contains Abu Qatadah al-Harrani, whom Ahmad and Yahya bin Ma'in, according to one report, declared thiqah (trustworthy), while a group declared him weak.