What is the ruling on repeatedly being preoccupied with the two rak'ahs before the Dawn prayer (Sunnat al-Fajr) to the extent of missing most of the congregational prayer (Salat al-Jama'ah), and what is the guidance of Islamic law in this regard?

When the congregational prayer is established, a worshiper is not permitted to engage in anything other than the prescribed prayer, due to the Prophet's (peace be upon him) saying: "When the prayer is established, there is no prayer except the prescribed one." The Hanafis' exception of the Fajr supererogatory prayer from this ruling is a weak opinion, for the following reasons:

1. The Prophet's (peace be upon him) prohibition to one who prayed when the Fajr prayer was established. 2. The Hadith of Abdullah ibn Sarjis, in which it is prohibited to perform a supererogatory prayer in a corner of the mosque while the congregational prayer is being established. 3. The weakness of the Hadith that exceptionalizes the Fajr supererogatory prayer from this ruling.

Moreover, the correct view is to make up the Fajr supererogatory prayer after the sun rises, or after the Fajr prayer, and not to perform it while the obligatory prayer is being established.