Salim bin Abdullah bin Umar narrates from his father that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) used to say: "Indeed, when Allah began this matter, He began it with prophethood and mercy; then it will return to caliphate and mercy, then to sovereignty and mercy, then to kingship and mercy, then it will become tyrannical rule (jabriyyah) in which people will bite one another the way donkeys bite one another. O people! Hold fast to jihad and military expeditions while they are sweet and fresh, before they become bitter and difficult, and before they become like scant grass and then decayed and crumbled. So when the expeditions become distant, the spoils are consumed, and the unlawful is treated as lawful, then hold fast to guarding the frontiers (al-ribat), for that will be your best jihad."