The ruling on praying the Sunnah prayer during the congregational prayer

Q: The brother (A. A. S.) says in his question: I see some of the worshippers—especially our Pakistani brothers—when they enter the mosque for the Fajr prayer and the imam has already begun the prayer, they do not enter with him directly. Instead, they pray the two rak'ahs of Fajr before entering with him. What is the ruling on their action? May Allah reward you with good.

A: This action is not permissible. It is obligatory for one who enters the mosque and the imam has already begun the prayer to enter with him. It is not permissible for him to be occupied with the greeting of the mosque or the rawatib (the regular voluntary prayers attached to the obligatory ones); because of the saying of the Prophet (peace and blessings be upon him): , as Muslim narrated in his Sahih from the hadith of Abu Hurayrah (may Allah be pleased with him). There is no difference between the rawatib of Fajr and the others.
It is prescribed for one who missed the Sunnah of Fajr to pray it after the prayer, or after the sun has risen, as the Sunnah of the Messenger of Allah (peace and blessings be upon him) has been authenticated to this effect.
And success is from Allah.