সহিহ মুসলিম ৪৫২৪

Sulaiman b. Buraida repotted on the authority of his father that when Allah's Messenger (ﷺ) sent an Amir with a detachment he called him and advised him. The rest of the hadith is the same

It has been narrated on the authority of Abu Masa that when the Messenger of Allah (ﷺ) deputed any of his Companions on a mission, he would say:Give tidings (to the people) ; do not create (in their minds) aversion (towards religion) ; show them leniency and do not be hard upon them

It has also been narrated by Sa'd b. Abu Burda through his father through his grandfather that the Prophet of Allah (ﷺ) sent him and Mu'adh (on a mission) to the Yemen, and said (by way of advising them):Show leniency (to the people) ; don't be hard upon them; give them glad tidings (of Divine favours in this world and the Hereafter) ; and do not create aversion. Work in collaboration and don't be divided