Performance Of A Prayer By One Who Is Sick

A sick person has to perform the prayer in accordance with the person's conditions. 

The Prophet Salallahu ‘alayhi wa sallam was once asked by a sick companion as to how he can perform the prayer and the Prophet Salallahu ‘alayhi wa sallam replied in as follows:

"Pray standing but if unable then by sitting and if still unable then do so whilst on your back".(Reported by Imam Bukhari,)

Thus:

1. If,  it is impossible for the sick person to stand up he/she shall perform the prayer by sitting and making token gestures for the Rukuu and Sujuud positions by bringing the head slightly down as indication  for Rukuu and slightly further down as indication for Sujuud.

2. If, it is possible for the sick person to pray sitting he/she shall perform the prayer by lying on his/her back. Allah Subhanahu Wa Ta’ala says:

".... those are they (men of understanding) who remember Allah while standing, sitting and reclining.." (Qur'an 3:190-191)

The person's legs are directed towards the Qiblah and will make more token gestures as far as possible with the head for the bowing(Rukuu) and the prostrations (Sujood) positions.

3. If ,still, it is impossible for the sick person to perform the prayer while lying as discussed in No. 2 above, then, the person shall perform the prayer by heart. The person shall come up with all the required recitations as far as possible, and will be recall to mind all the necessary postures for the prayer.

Such is the importance of the prayer in Islam that a person must perform it no matter what his/her condition.