From Sahih Bukhari (Hadith 4468):
Narrated Salim's father:The Prophet (ﷺ) appointed Usama as the commander of the troops (to be sent to Syria). The Muslims spoke about Usama (unfavorably ). The Prophet (ﷺ) said, " I have been informed that you spoke about Usama. (Let it be known that ) he is the most beloved of all people to me
Reference: Bukhari 4468