How a sick person can perform Salat
1. It is obligatory for the sick person to pray standing, even if leaning, or propped against a wall or on a crutch or staff, if he needs the support.
2. If he can’t stand, he should pray sitting, and the best thing is for him to sit cross-legged in the position of Qayam and Ruku.’
3. If he can’t sit, he should lie on his side, facing Qiblah; and the right side is better to lie on. If he can’t manage to face the Qiblah, he should face wherever he’s facing, and his Salat is valid, and he doesn’t have to repeat it later.
4. If he can’t offer the Salat lying his side, he should lie on his back with his feet towards the Qibla and if he’s able, it is better for him to have his head propped up a bit so that he has got his face towards Qiblah; again, if he can’t get his feet facing Qiblah, he should pray wherever he’s facing and he doesn’t have to repeat later.
5. It is obligatory for the sick person to perform Ruku’ and Sajdah in his Salat. If he is unable, he can make a gesture with his head, making the gesture for Sajdah more prominent than the gesture for Ruku". If he is able to perform Ruku but not Sajdah, he should perform Ruku’ normally then make the substitute gesture for Sajdah. And if he is able to perform Sajdah, he should perform Sajdah where called for and make the substitute gesture for Ruku’, and it is not necessary to get a pillow to perform Sajdah on.
6. If he cannot move his head, he should make the signal for Ruku’ and Sajdah with his eyes, lowering his eyelids slightly for Ruku’ , and more for Sajdah. As for gesturing with one’s finger, as some sick people do, it is not correct, and I know of no basis for it in the Qur’an or Sunnah or statements of the scholars.
7. If he is unable to gesture with his head nor with his eyes, he should pray in his heart, saying Takbir and reciting, and making intention for Ruku’ and Sajdah and standing and sitting in his heart, and everyone will be rewarded according to their intention.
8. It is mandatory for the sick person to pray every Salat at its appointed time, and to perform every act of it according to his ability. If it proves difficult for him to pray each Salat on time, he can join Zuhr and ‘Asr, and Magrib and ‘Isha together by delaying the first or offering second earlier, whatever is easier for him. As for Fajr, it must be prayed at its regular time, without joining it to what is before it nor to what is after it.
9. If the sick person travels for medical treatment to another country or city, he may shorten his four Rak’a Salat, praying Zuhr, Asr and ‘Isha, each as two Rak’a, until he returns to his own place, whether the period of his journey is long or short (this is according to Shaikh Muhammad Salih Uthaimin).