Ruling 956 — Prayer (Ṣalāh)

As long as a person is able to perform prayers in a standing position, he must not sit down. For example, someone whose body shakes when he stands or is compelled to lean on something or incline his body a little, must perform prayers in a standing position in whatever way he can. However, if he cannot stand at all, he must sit straight and perform prayers in a sitting position.