Musannaf Ibn Abi Shaybah 35612 — Campaigning with unjust rulers

Abu Jamrah (may Allah have mercy on him) said: I asked Sayyiduna Ibn Abbas (may Allah be pleased with them both): What about fighting together with those rulers who have introduced new things into the religion and committed oppression? He said: You fight for your share of the Hereafter (the reward), and they fight for their share of this world.