Sahih al-Bukhari 4837
Sahih al-Bukhari · Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · The Statement of Allah the Exalted: "That Allah may forgive you your sins of the past and the future and complete His Favour on you and guide you on the Straight Path." (V.48:2)
Narrated Aisha:
حَدَّثَنَا الْحَسَنُ بْنُ عَبْدِ الْعَزِيزِ ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يَحْيَى ، أَخْبَرَنَا حَيْوَةُ ، عَنْ أَبِي الأَسْوَدِ ، سَمِعَ عُرْوَةَ ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ أَنَّ نَبِيَّ اللَّهِ صلى الله عليه وسلم كَانَ يَقُومُ مِنَ اللَّيْلِ حَتَّى تَتَفَطَّرَ قَدَمَاهُ فَقَالَتْ عَائِشَةُ لِمَ تَصْنَعُ هَذَا يَا رَسُولَ اللَّهِ وَقَدْ غَفَرَ اللَّهُ لَكَ مَا تَقَدَّمَ مِنْ ذَنْبِكَ وَمَا تَأَخَّرَ قَالَ " أَفَلاَ أُحِبُّ أَنْ أَكُونَ عَبْدًا شَكُورًا " . فَلَمَّا كَثُرَ لَحْمُهُ صَلَّى جَالِسًا فَإِذَا أَرَادَ أَنْ يَرْكَعَ قَامَ، فَقَرَأَ ثُمَّ رَكَعَ .
The Prophet (ﷺ) used to offer prayer at night (for such a long time) that his feet used to crack. I said, "O Allah's Messenger (ﷺ)! Why do you do it since Allah has forgiven you your faults of the past and those to follow?" He said, "Shouldn't I love to be a thankful slave (of Allah)?' When he became old, he prayed while sitting, but if he wanted to perform a bowing, he would get up, recite (some other verses) and then perform the bowing.