Musnad Abu Ya'la al-Mawsili 117:241

Zuhayr narrated to us, Affan narrated to us, Hammad narrated to us, Thabit informed us, from Anas, that when the people of Yemen came to the Messenger of Allah (may Allah bless him and grant him peace), they said: "Send with us a man who will teach us the Sunnah and Islam." He took the hand of Abu Ubaydah ibn al-Jarrah and said: "This is the trustworthy one of this nation."