Does the prayer of the congregant become void if he precedes the imam in bowing (ruku‘) and prostration (sujud), or if he lags behind by the imam raising his head before the congregant completes the pillar of bowing or prostration, without a valid excuse?

If the congregant joins his Imam in bowing or prostrating, then deliberately raises from them before the Imam, he is sinful and must return to perform what he preceded the Imam in. If he does not do so deliberately, his prayer is invalidated according to some scholars. His prayer is not invalidated if he was ignorant or forgetful. As for a congregant lagging behind his Imam by a full pillar without an excuse, it is said that this invalidates the prayer.