“The Messenger of Allah ﷺ used to pray 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?’” (Using translation from Ibn Mājah 1420)
كَانَ النَّبِيُّ ﷺ يُصَلِّي حَتَّى تَرِمَ قَدَمَاهُ فَقِيلَ لَهُ أَلَيْسَ قَدْ غَفَرَ اللهُ لَكَ مَا تَقَدَّمَ مِنْ ذَنْبِكَ وَمَا تَأَخَّرَ؟ قَالَ أَفَلَا أَكُونُ عَبْدًا شَكُورًا