A Masbuq is a person who joins the congregational prayer after the Imam has already completed one or more units (Rak'ahs). There are specific rules for a Masbuq to ensure their prayer is valid: they must join the congregation in whatever position the Imam is currently in (bowing, prostrating, etc.), and after the Imam performs the final Salam, the Masbuq must stand up without saying Salam to complete the missed portions of their prayer. The concept of the Masbuq ensures that no one is excluded from the blessings of the congregation, even if they arrive late.