What is the prayers of the ill? What prayer is performed when sick? How do you pray when you are sick? Which surah to recite for illness?
Islam is the religion of ease. No one is burdened with more than they can bear. The ill are provided with facilities in terms of their acts of worship as much as they are able to do.
An ill person is obliged to pray according to his strength. For example, a patient who is unable to stand or if it is known that standing will cause the prolongation of his illness or worsen it can pray by sitting, or if he is unable to sit, he can pray by lying on his side or his back, depending on the situation.
The proof of this ease is based on the following hadith:
When Imrān Ibn Ḥusayn (ra), who had hemorrhoids, asked the Messenger of Allah (saw) how to perform his ritual prayer, the Messenger of Allah (saw) said, “Stay standing, if you are not able to do so, sit down, and if you are not able, perform it by leaning.”
When it is not possible to perform bowing and prostration in a normal way, the ritual prayer is performed with gestures. Praying with gestures means bowing the head in prayer as a sign of rukūʿ and prostration. Praying with gestures can be done standing up or sitting down, lying on one’s side, or on one’s back.
 Al-Bukhari, Taqṣīr, 19; Abū Dawūd, Ṣalāh, 175; al-Tirmidhī, Ṣalāh, 157; Ibn Maja, ‘Iqāmah, 139. The Prophet (saw) on this subject cited the beginning of the 286th verse of al-Baqara (2) as evidence.
 For more information, see the topics of the pillars of prayer, “qiyām” and “those with chronic excuses”.
Source: Basic Islamic Principles (ilmiḥal) According to the Four Sunni Schools With Evidence From The Sources of Islamic Law, Prof. Hamdi Döndüren, Erkam Publications