Sahih Muslim #4526 · The Book of Jihad and Expeditions

Sahih MuslimIt has also been narrated by Sa'd b. Abu Burda through his father through his grandfather that the Prophet of Allah
Sahih Muslim · Book 32 · The Book of Jihad and Expeditions
Sahih Muslim · كتاب 32 · كتاب الجهاد والسير
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.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ شُعْبَةَ، عَنْ سَعِيدِ بْنِ أَبِي بُرْدَةَ، عَنْ أَبِيهِ، عَنْ جَدِّهِ، أَنَّ النَّبِيَّ صلى الله عليه وسلم بَعَثَهُ وَمُعَاذًا إِلَى الْيَمَنِ فَقَالَ ‏
"‏ يَسِّرَا وَلاَ تُعَسِّرَا وَبَشِّرَا وَلاَ تُنَفِّرَا وَتَطَاوَعَا وَلاَ تَخْتَلِفَا ‏"‏ ‏.‏
Reference : Sahih Muslim 4526In-book reference : Book 32, Hadith 7