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)?" (Using translation from Bukhārī 4836)
أَنَّ النَّبِيَّ ﷺ كَانَ يُصَلِّي حَتَّى تَرِمَ قَدَمَاهُ فَقِيلَ لَهُ يَا رَسُولَ اللَّهِ إِنَّ اللَّهَ ﷻ قَدْ غَفَرَ لَكَ مَا تَقَدَّمَ مِنْ ذَنْبِكَ وَمَا تَأَخَّرَ قَالَ «أَفَلَا أَكُونُ عَبْدًا شَكُورًا؟»