Let another man praise you, and not your own mouth; a stranger, and not your own lips.
All Commentaries on Proverbs 27:2 Go To Proverbs 27
Augustine of Hippo
AD 430
If I seem arrogant to you, it is for this reason, that I bear testimony to myself. For every person, when he wishes to bear praiseworthy testimony to himself, seems arrogant and proud. So it has been written, “Let not your own mouth praise you, but let the mouth of your neighbor praise you.” .