From Sahih Muslim (Hadith 6254):
Hudhaifa reported that the people of Najran came to Allah's Messenger (ﷺ) and said:Allah's Messenger, send along with us a man of trust; whereupon he said: I would definitely send to you a man of trust, a man of trust in the true sense of the term. Thereupon his Companions looked up eagerly and he sent Abu Ubaida b. Jarrah
Reference: Muslim 6254