The Prophet (ﷺ) said, "For every nation there is an Amin (honest, trustworthy person) and the Amin of this nation is Abu 'Ubaida."
Sahih al-Bukhari Book 95, Hadith 10
← Previous Hadith The Prophet (ﷺ) said to the people of Najran, "I will send to you an honest person who is really trustworthy." The Companion, of the Prophet (ﷺ) each desired to be that person, but the Prophet (ﷺ) sent Abu 'Ubaida.

Sahih al-Bukhari Book 95, Hadith 9 Next Hadith → There was a man from the Ansar (who was a friend of mine). If he was not present in the company of Allah's Messenger (ﷺ) I used to be present with Allah's Messenger (ﷺ), I would tell him what I used to hear from Allah's Messenger (ﷺ), and when I was absent from Allah's Messenger (ﷺ) he used to be present with him, and he would tell me what he used to hear from Allah's Messenger (ﷺ) .

Sahih al-Bukhari Book 95, Hadith 11