"I asked Messenger of Allah (S) about the Salat for a man who is sitting. He said: 'Whoever performs Salat while standing then that is more virtuous. And whoever performs Salat while sitting, then he gets half the rewards of the one standing, and whoever performs Salat while lying down, then he gets half the rewards of the one sitting.'"  

سَأَلْتُ رَسُولَ اللَّهِ ﷺ عَنْ صَلاَةِ الرَّجُلِ وَهُوَ قَاعِدٌ فَقَالَ مَنْ صَلَّى قَائِمًا فَهُوَ أَفْضَلُ وَمَنْ صَلَّى قَاعِدًا فَلَهُ نِصْفُ أَجْرِ الْقَائِمِ وَمَنْ صَلَّى نَائِمًا فَلَهُ نِصْفُ أَجْرِ الْقَاعِدِ قَالَ وَفِي الْبَابِ عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو وَأَنَسٍ وَالسَّائِبِ وَابْنِ عُمَرَ  

"From Imran bin Husain who said: 'I asked Messenger of Allah (S) about Salat for a sick person. He said: "He performs Salat standing, if he is not able then sitting, if he is not able then on his side."  

سَأَلْتُ رَسُولَ اللَّهِ ﷺ عَنْ صَلاَةِ الْمَرِيضِ فَقَالَ صَلِّ قَائِمًا فَإِنْ لَمْ تَسْتَطِعْ فَقَاعِدًا فَإِنْ لَمْ تَسْتَطِعْ فَعَلَى جَنْبٍ حَدَّثَنَا بِذَلِكَ هَنَّادٌ حَدَّثَنَا وَكِيعٌ عَنْ إِبْرَاهِيمَ بْنِ طَهْمَانَ عَنْ حُسَيْنٍ الْمُعَلِّمِ بِهَذَا الْحَدِيثِ