الشمائل المحمدية

It is also reported from Abu Huraira, may Allah be well pleased with him that: Allah’s Messenger (Allah bless him and give him peace) used to stand performing the ritual prayer until his feet had begun to swell, so he would be asked: “O Messenger of Allah, must you do this, when Allah has already forgiven you your former and your latter sins?” He replied: “Shall I not be a thankful servant?”