عَنْ عِمْرَانَ بْنِ حُصَيْنٍ رَضِيَ اللَّهُ عَنْهُ قَالَ: كَانَ بِيَ النَّاصُورُ فَسَأَلْتُ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ عَنِ الصَّلَاةِ، فَقَالَ: ((صَلِّ قَائِمًا فَإِنْ لَمْ تَسْتَطِعْ فَقَاعِدًا، فَإِنْ لَمْ تَسْتَطِعْ فَعَلَى جَنْبٍ))
Sayyiduna Imran bin Husain (may Allah be pleased with him) says: I was suffering from a fistula, so I asked the Noble Prophet (peace and blessings be upon him) about prayer. He (peace and blessings be upon him) said: Perform the prayer standing; if you are not able to stand, then pray sitting; and if you are not able to sit, then pray lying on your side.