Musnad Ahmad 189:2

Bakr ibn Isa narrated to us, he said: Abu Awanah narrated to us, from Asim al-Ahwal, from Abu Uthman al-Nahdi, from Mujashi ibn Masud, who said: I went with my brother, Ma'bad, to the Messenger of Allah, may Allah bless him and grant him peace, after the Conquest. I said: "O Messenger of Allah, accept his pledge of allegiance for migration." He said: "Migration has passed for its people." I said: "Then upon what?" He said: "Upon Islam and Jihad."