Ibn Aun says: I wrote to Imam Nafi’ asking these questions: What kept Sayyiduna Ibn Umar (may Allah be pleased with him) from participating in battles or staying behind from those who went out for jihad? Before fighting the enemy, what should they first be invited to? And can a person attack an army without the permission of the Imam? He replied in writing: The son of Sayyiduna Ibn Umar (may Allah be pleased with him) is engaged in jihad and he (Ibn Umar) provides mounts, and he also says that after prayer, the most virtuous deed is jihad in the way of Allah. But what kept Sayyiduna Ibn Umar (may Allah be pleased with him) from going out to battle were the bequests of Sayyiduna Umar (may Allah be pleased with him), young children, and abundant wealth. The Messenger of Allah (peace and blessings be upon him) launched a night attack on Banu Mustaliq while they were unaware and watering their camels, so he (peace and blessings be upon him) killed their warriors and took the rest captive. In this battle, the Prophet (peace and blessings be upon him) acquired Lady Juwayriya bint al-Harith (may Allah be pleased with her) as a captive. Sayyiduna Ibn Umar (may Allah be pleased with him) narrated this hadith to me, and he was present in that army as well. The disbelievers should first be invited to Islam, and a person should not attack an army without the permission of the Imam.