Q. Sometimes a person is late for Salaah and he joins the Imaam in the last Rakaat of the sitting posture of Salaah and before the Imaam makes Salaam or whilst the Imaam is making Salaam a person joins the Salaah and makes Takbeer but before he reaches the sitting posture of Salaah the Imaam already completes the Salaam, is his Salaah valid?
A. If a late comer of Salaah (Masbooq) says the Takbeer and joins the Imaam in Salaah before the Imaam makes Salaam, then his following of the Imaam and his Salaah will be valid and he should complete his remainder of his Salaah even though the late comer (Masbooq) did not join the Imaam in the sitting posture of Salaah after saying Takbeer.
However, if the Imaam made Salaam and then a later comer of Salaah (Masbooq) says the Takbeer, the following of the late comer of Salaah (Masbooq) will not be valid. Hence, he would be required to make a new Takbeer and perform his Salaah separately. (Shaami 1/468)
Allah Ta’ala Knows Best
Mufti Ismaeel Bassa
This answer was collected from TheMufti.com, which is a fatwa portal managed by Mufti Ismaeel Bassa from South Africa.