Sahih al-Bukhari 4836
Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · Narrated by Al-Mughira
Arabic
حَدَّثَنَا صَدَقَةُ بْنُ الْفَضْلِ، أَخْبَرَنَا ابْنُ عُيَيْنَةَ، حَدَّثَنَا زِيَادٌ، أَنَّهُ سَمِعَ الْمُغِيرَةَ، يَقُولُ قَامَ النَّبِيُّ صلى الله عليه وسلم حَتَّى تَوَرَّمَتْ قَدَمَاهُ فَقِيلَ لَهُ غَفَرَ اللَّهُ لَكَ مَا تَقَدَّمَ مِنْ ذَنْبِكَ وَمَا تَأَخَّرَ قَالَ " أَفَلاَ أَكُونُ عَبْدًا شَكُورًا ".
English translation
Narrated Al-Mughira:The Prophet (ﷺ) used to offer night prayers till his feet became swollen. Somebody said, to him," "Allah has forgiven you, your faults of the past and those to follow." On that, he said, "Shouldn't I be a thankful slave of Allah)?
Reference: Sahih al-Bukhari 4836, Book of Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)). English translation by Dr. Muhammad Muhsin Khan.