What is the ruling on the prayer of a latecomer who completed what he missed and then performed the prostration of forgetfulness (sujud al-sahw) after the imam's salutation, and the latecomer who performed the prostration of forgetfulness with the imam after his salutation and then completed what he missed? And what is the correct action to take in this situation?

Scholars have differed regarding whether a latecomer (masbuq) should follow the Imam in the prostration of forgetfulness (sujood as-sahw). The majority of scholars hold that the follower should follow the Imam. However, the Malikis and Shafi'is are of the opinion that the latecomer should first make up what he missed and then perform the prostration. This is also narrated from Ahmad if the latecomer has begun recitation.

If the Imam prostrates after the latecomers have stood up, then whoever continues to complete their prayer and performs the prostration of forgetfulness after finishing the prayer has done what is correct. As for whoever returns from standing to prostrate with the Imam: if the Imam prostrated before the latecomer stood up fully, then returning is obligatory for him. If the Imam prostrated after he stood up fully, he should not return unless he has not started reciting. However, if he has started reciting, it is not permissible for him to return.