Musnad Ahmad 32:2104

'Affan narrated to us, Hammad narrated to us, Thabit narrated to us, from Anas, that when the people of Yemen came to the Messenger of Allah (peace and blessings of Allah be upon him), they said: "Send with us a man to teach us the Sunnah and Islam." He said: So he took the hand of Abu 'Ubaydah ibn al-Jarrah and said: "This is the trustworthy one of this nation."