Sayyiduna Anas (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) would stand (in voluntary prayer) for so long that his (peace and blessings be upon him) feet (the narrator is in doubt; perhaps the words are:) his (peace and blessings be upon him) shins would become swollen. It was said to him (peace and blessings be upon him) about this: "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?"
Abu Ya'la, al-Bazzar and al-Tabarani in al-Mu'jam al-Awsat recorded it, and its narrators are the narrators of the Sahih.
Hadith Takhrij«مسند أبى يعلى الموصلي، قتادة 2830 معجم ابن الأعرابي 691 المعجم الأوسط للطبراني، باب العين باب الميم من اسمه محمد ، 5844 التهجد وقيام الليل لابن أبى الدنيا باب ذكر القائمين حتى تورمت أقدامهم 213»