From Sahih Bukhari (Hadith 3745):
Narrated Hudhaifa:The Prophet (ﷺ) said to the people of Najran, "I will send you the most trustworthy man." (Every one of) the companions of the Prophet (ﷺ) was looking forward (to be that person). He then sent Abu 'Ubaida
Reference: Bukhari 3745