How does a sick person pray who is unable to sit after standing, nor stand after sitting?

The worshipper must perform what he is able to, and what he is unable to perform is waived, according to the verse: (So fear Allah as much as you are able), and the saying of the Prophet, peace and blessings be upon him: (When I command you to do something, do as much of it as you are able).

Therefore, if the worshipper is able to begin the prayer standing, it is obligatory for him to do so. He should bow completely if he is able, otherwise, he should incline as much as he is able. If he is able to prostrate on the ground, it is obligatory for him to do so, otherwise, he should sit (on the ground or a chair) and incline for prostration. If he is unable to stand again, he completes his prayer sitting, inclines when bowing, and prostrates on the ground if he is able, otherwise, he inclines for prostration, making the inclination for prostration lower than for bowing.

If he is able to stand and lie down, but unable to sit, he prays standing, and gestures for bowing and prostration, and recites the tashahhud and gives salutations while standing. If he is unable to stand, he prays sitting, and gestures for bowing and prostration. If he is able to prostrate on the ground, it is obligatory for him to do so.

If a sick person finds that he must either stand for the entire prayer or sit for the entire prayer, he should pray sitting.