عَنِ الْمُغِيرَةِ بْنِ شُعْبَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ يُصَلِّي حَتَّى تَرِمَ قَدَمَاهُ (وَفِي رِوَايَةٍ: قَامَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ حَتَّى تَوَرَّمَتْ قَدَمَاهُ)، فَقِيلَ لَهُ: أَلَيْسَ قَدْ غَفَرَ اللَّهُ لَكَ مَا تَقَدَّمَ مِنْ ذَنْبِكَ وَمَا تَأَخَّرَ؟ قَالَ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((أَفَلَا أَكُونُ عَبْدًا شَكُورًا))
Sayyiduna Mughira bin Shu’bah (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings be upon him) used to perform (such lengthy) prayers at night that his feet would swell. Someone said to him: Has Allah not forgiven all your past and future sins? (Then why do you stand for such a long time?) The Prophet (peace and blessings be upon him) replied: Should I not be a most grateful servant of Allah?