The Prophet (may Allah's peace and blessings be upon him) sent Khālid ibn al-Walīd to the people of Yemen to invite them to Islam, but they did not respond to him. Then, the Prophet sent ‘Ali ibn Abi Tālib

Al-Barā' (may Allah be pleased with him) reported: The Prophet (may Allah's peace and blessings be upon him) sent Khālid ibn al-Walīd to the people of Yemen to invite them to Islam, but they did not respond to him. Then, the Prophet sent ‘Ali ibn Abi Tālib and ordered him to send back Khālid and those with him except if any of the men with Khālid wanted to stay with ‘Ali, in which case they should be allowed to do so. I was one of those who stayed with him. When we drew close to the people, they went out toward us, and ‘Ali (may Allah be pleased with him) led us in prayer and lined us in one row. Then, he stepped forward and stood before us and read out the Messenger’s letter to them. Thereupon, the entire Hamdān tribe embraced Islam. ‘Ali (may Allah be pleased with him) wrote to the Messenger of Allah (may Allah’s peace and blessings be upon him) informing him of their conversion to Islam. On reading that, the Messenger of Allah (may Allah’s peace and blessings be upon him) fell in prostration. Then, he raised his head and said: "Peace be upon Hamdān, peace be upon Hamdān."