He served as the chief judge and commander of the security forces in Egypt under the governor Amr ibn al-As.
[5] After the fall of Babylon in April 641, Amr dispatched Kharija to conquer the Fayyum oasis, Hermopolis, Akhmim, Bashrudat and the villages of Upper Egypt and make similar terms with their inhabitants.
[5][6] While Amr was away besieging Alexandria, he left Kharija as his deputy over the Arab capital in Egypt, Fustat.
[6] He made Kharija the qadi (chief judge) of Egypt, where he became popular, and the head of his shurta (select troops or security forces).
[7] As opposition to Uthman culminated with a siege of his house in Medina, Kharija was at the forefront of those in Egypt calling to support the caliph.