What is the ruling on starting to make up missed rak'ahs before the imam finishes the two taslims? And how many taslims are there for obligatory prayers? And does reciting dhikr necessitate staying in the prayer area?

Scholars have differed regarding the tasleem (salutation) at the end of prayer. The Hanafis hold that it is a sunnah (recommended practice). The Malikis believe that only one tasleem is prescribed. The Shafi'is, and one narration among the Hanbalis preferred by Ibn Qudamah, maintain that the first tasleem is obligatory and the second is mustahabb (desirable). The second narration among the Hanbalis, which is the adopted view among later scholars, states that both tasleemat are a rukn (integral pillar). The preponderant view is that the first tasleem is a rukn and the second is mustahabb.

Ibn Qudamah holds that only one tasleem is obligatory, and the second is sunnah, citing Ibn al-Mundhir's consensus on the permissibility of confining oneself to a single tasleem, as well as the practice of the Prophet (peace be upon him) and the Companions.

The difference of opinion regarding tasleem branches out to the issue of when a latecomer (masbooq) should stand to make up what he missed. The Hanbalis, who deem both tasleemat obligatory, stipulate that the masbooq should not stand before the Imam's second tasleem; otherwise, his obligatory prayer becomes invalid and turns into a supererogatory one. As for those who consider the second tasleem mustahabb, they permit the masbooq to stand after the first tasleem, though it is mustahabb for him to wait until the Imam completes both tasleemat.

The most cautious approach to avoid disagreement is for the masbooq not to stand until the Imam has completed both tasleemat. Preparing to stand without actually standing does not affect the validity of the prayer.