Issue: Is it valid to pray behind an imam who is unable to bow, prostrate, or sit?

It has already been mentioned that, according to the established school, prayer behind him is not valid unless the follower is in the same condition.

However, the correct view is that prayer behind him is valid, based on the principle that whoever’s prayer is valid may lead the prayer, unless there is evidence to the contrary. This principle is indicated by the general texts, except in the case of a woman: she may not lead a man in prayer, because she is of a different sex.

Moreover, this may be analogized to one who is unable to stand. The prayer of one capable of standing behind one incapable of standing is valid by explicit text; likewise, then, is prayer behind one unable to bow or prostrate.

If someone were to say: The Prophet, peace and blessings be upon him, said, “If he prays standing, then pray standing; and if he prays seated, then pray seated, all of you” (1), but he did not say, “If he bows, then bow; and if he gestures, then gesture”?

We say: The hadith mentioned standing only because it was spoken in the case of an inability to stand. The Messenger, peace and blessings be upon him, addressed them when he led them in prayer seated while they were standing; then he gestured to them, and they sat. Thus, the Prophet, peace and blessings be upon him, mentioned standing as an example, because that was what had occurred.

Accordingly, we say that the preponderant view is that prayer behind one unable to bow is valid. Thus, if our imam were unable to bow because of pain in his back, we would pray behind him.