Proverbs 27:2

Let another man praise thee, and not thine own mouth
Men should do those things which are praiseworthy; and should do them openly, that they may be seen and praised for them: for it is honourable to have such a character as Demetrius had, who had a good report of all men; and as the brother had, whose praise in the Gospel was in all the churches. To be commended by others, by any but a man's self, is to his credit and reputation; but nothing more hurtful to it than self-commendation; see ( 2 Corinthians 10:18 ) ; in some cases it is right for a man indeed to commend himself, when the glory of God, the credit of religion, the cause of truth and self-vindication, require it; as the prophet Samuel, the Apostle Paul, and others, have been obliged to do, ( 1 Samuel 12:3 ) ( 2 Corinthians 11:12 )

a stranger, and not thine own lips;
a stranger means any other than a man's self; and if it is one that he knows not, or has little acquaintance with; or if a foreigner, that does not personally know him, only has good testimonies of him, or has read his works; and especially if in other respects an enemy; it is greatly to his honour to be praised by him: and such a commendation comes with much better grace than from himself, and from whom indeed it would not come with any.