The Prophet ﷺ sent him along with Muaz to Yemen and said, "Make things easy and do not make them difficult, give glad tidings and do not drive people away, and cooperate with one another and do not differ."
ى، أن النبي ﷺ بعثه ومعاذا إلى اليمن، فقال: يسرا ولا تعسرا، بشرا ولا تنفرا، وتطاوعا ولا تختلفا.
Bukhari related it in the Book of Jihad and Expeditions (3038), and Muslim in the Book of Jihad and Expeditions (1733), both from the hadith of Waki, from Shuba, from Saeed bin Abu Burda, from his father, from Abu Musa Ashari, who mentioned it.