For how many hours did the righteous predecessors sleep, and how did they resist sleep in pursuit of knowledge?

Allah blessed the righteous predecessors in their times due to the strength of their faith and their sincerity. They slept but little at night and strove against their souls in seeking knowledge and persevering in it, like the journey of Jabir ibn Abdullah, which was a month's travel for a single hadith. The exact number of their sleeping hours is not precisely known, but it was little.