His statement, “then he must”: the word “must” indicates obligation. That is, he must return so that he may perform it after his imam. He is required to return for the sake of following the imam, because by returning he performs it after his imam. This bowing or prostration that took place before the imam’s bowing or prostration is not legally valid, since it was done out of its proper place. The Prophet ﷺ said, “When he bows, then bow; and when he prostrates, then prostrate.” (1) Thus, if he bows before him or prostrates after him, he has performed it outside its proper place, so it is invalid. This is why we deemed it obligatory for him to return and perform it after the imam.

It is understood from the implication of the author’s words that this action is prohibited—that is, for the follower to bow before the imam or to prostrate before the imam—and that is indeed the case.

The evidence for this is the Prophet’s ﷺ statement: “Do not bow until he bows, and do not prostrate until he prostrates.” (2) The basic principle concerning a prohibition is that it denotes unlawfulness. Indeed, if someone were to say that this is among the major sins, he would not be far from the truth, due to the Prophet’s statement: “Does the one who raises his head before the imam not fear that Allah may transform his head into the head of a donkey, or make his appearance that of a donkey?” (3) This is a threat, and a threat is one of the signs that a sin is among the major sins. Accordingly, we say that this man has committed one of the major sins for which he has been threatened with Allah transforming his head