It is reported that Imām Al-Awzā’ī – Allāh have mercy on him – said:

At the time of Fajr, or a while before it, the Salaf would be as if birds were sitting on their heads: (still ) concentrating on themselves [and their worship], so much so that even if one of their closest friends came to them after having been parted from them, they would not notice him. They would remain in this state until just before sunrise. Then, they would meet each other and sit in the circles. The first thing they would discuss is the matter of their afterlife and what would become of them in the hereafter. Then they would begin the circles of Quran and Fiqh study.

Ibn ‘Asākir, Tārīkh Dimishq 35:184, 185.