It is narrated from Hazrat Anas (may Allah be pleased with him) that when the people of Yemen came to the service of the Prophet (peace and blessings be upon him), they requested the Prophet (peace and blessings be upon him) to send a man with them who would teach them the religion. The Prophet (peace and blessings be upon him) sent Hazrat Abu Ubaidah (may Allah be pleased with him) with them and said, "He is the trustworthy one of this Ummah."