Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) sent me to Yemen and said: "Perhaps you will pass by my mosque and my grave. I have sent you to a people whose hearts are tender; they will fight for the truth. So fight, with those of them who obey you, those who disobey you. Then they will return to Islam, until the wife will race her husband, the son his father, and the brother his brother (to Islam). So settle between the two tribes, al-Sakun and al-Sakasik."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17307