As an adult, he gave most of his money as alms and went to the desert of St. Macarius the Great and became a monk.
When Abba Marcus II became the 49th Pope of Alexandria, he summoned Yousab, ordained him a priest and sent him back.
He stayed in the desert until the death of Abba Simon II, 51st Pope.
[1] The papal throne remained unoccupied, and Abba Yousab was chosen Pope.
Abba Yousab condemned actions of bishops of Tanes and Miser (Cairo); they were excommunicated.