Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 275
Narrated Abu Burda:
That his father said, "The Prophet sent Mu'adh and Abu Musa to Yemen telling them. 'Treat the people with ease and don't be hard on them; give them glad tidings and don't fill them with aversion; and love each other, and don't differ."