Silsilah as-Sahihah 2811 — Methods of Preaching by Preachers

It is narrated from Sayyiduna Abu Musa (may Allah be pleased with him), he says that when the Prophet (peace and blessings be upon him) would appoint a companion as a leader over some of his affairs, he would say: "Give glad tidings, do not make people averse, make things easy, and do not make things difficult."