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?’”
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ زِيَادِ بْنِ عِلاَقَةَ، سَمِعَ الْمُغِيرَةَ، يَقُولُ قَامَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ حَتَّى تَوَرَّمَتْ قَدَمَاهُ . فَقِيلَ يَا رَسُولَ اللَّهِ قَدْ غَفَرَ اللَّهُ لَكَ مَا تَقَدَّمَ مِنْ ذَنْبِكَ وَمَا تَأَخَّرَ . قَالَ " أَفَلاَ أَكُونُ عَبْدًا شَكُورًا " .
IbnMaja
Establishing the Prayer and the Sunnah Regarding Them • Hadith 1419