Sahih al-Bukhari 1117
Sahih al-Bukhari · Book 18: Shortening the Prayers (At-Taqseer) · Whoever cannot offer Salat while sitting, can offer Salat while lying on his side
Narrated `Imran bin Husain:
حَدَّثَنَا عَبْدَانُ ، عَنْ عَبْدِ اللَّهِ ، عَنْ إِبْرَاهِيمَ بْنِ طَهْمَانَ ، قَالَ حَدَّثَنِي الْحُسَيْنُ الْمُكْتِبُ ، عَنِ ابْنِ بُرَيْدَةَ ، عَنْ عِمْرَانَ بْنِ حُصَيْنٍ ـ رضى الله عنه ـ قَالَ كَانَتْ بِي بَوَاسِيرُ فَسَأَلْتُ النَّبِيَّ صلى الله عليه وسلم عَنِ الصَّلاَةِ فَقَالَ " صَلِّ قَائِمًا، فَإِنْ لَمْ تَسْتَطِعْ فَقَاعِدًا، فَإِنْ لَمْ تَسْتَطِعْ فَعَلَى جَنْبٍ " .
had piles, so I asked the Prophet (ﷺ) about the prayer. He said, "Pray while standing and if you can't, pray while sitting and if you cannot do even that, then pray Lying on your side."