Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Bukhari :: Book 5 :: Volume 59 :: Hadith 599
Narrated Mujashi bin Masud:
I took Abu Mabad to the Prophet in order that he might give him the pledge of allegiance for migration. The Prophet said, "Migration has gone to its people, but I take the pledge from him (i.e. Abu Mabad) for Islam and Jihad."