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."
أن النبي ﷺ بعثه ومعاذا إلى اليمن فقال: يسرا ولا تعسرا، وبشرا ولا تنفرا، وتطاوعا ولا تختلفا.
Bukhari narrated it in the Book of Jihad and Expeditions (3038), and Muslim in the Book of Jihad and Expeditions (1733:7), both by way of Waki, from Shubah, from Saeed bin Abu Burda, from his father, from his grandfather, who said, and then he recounted it.