What is the ruling on the prayer of a latecomer who caught the last tashahhud or the last rak’ah with the Imam, then after making up what he missed, it became clear that there was a missing rak’ah in the Imam’s prayer, so the Imam and those with him repeated the prayer? And what if the worshipper stood up to make up what he missed, then the Imam realized the deficiency and stood to make it up, should the latecomer follow him again or complete what he missed separately?

If a latecomer (masbuq) stands up to complete his prayer, then realizes that the Imam has not yet finished his prayer, he must return to follow the Imam. What he did before returning is not counted, and he is not required to perform sujud sahv (prostration of forgetfulness) because the ruling of following the Imam remains. If the Imam performs sujud sahv before the salam, the latecomer follows him. If the Imam performs sujud sahv after the salam, the latecomer performs sujud sahv after his own salam. If the latecomer does not return and begins to complete his prayer, his prayer becomes void and he must repeat it. However, if the Imam interrupts his prayer and starts a new prayer, he has made a mistake. In this case, some scholars are of the opinion that the prayer of the congregant becomes void, while others hold that the congregant should intend to separate and complete his prayer by himself.