Let another man give you praise, and not your mouth; one who is strange to you, and not your lips.

Let another praise you, and not your own mouth: an outsider, and not your own lips.

Another - An "alienus" rather than "alius." Praise to be worth anything must be altogether independent.

Let another man praise thee, and not thine own mouth - We have a similar proverb, which illustrates this: "Self-praise is no commendation."

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, &c.
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.

There may be occasion for us to justify ourselves, but not to praise ourselves.

Avoid self-praise.

2 Let another praise thee, and not thine own mouth;
A stranger, and not thine own lips.
The negative לא is with פיך, as in (Arab.) ghyra fyk, bound into one compact idea: that which is not thine own mouth (Fleischer), "not thine own lips," on the other hand, is not to be interpreted as corresponding to it, like אל־מות, Proverbs 12:28; since after the prohibitive אל, יהללוּך [praise thee] easily supplies itself. זר is properly the stranger, as having come from a distance, and נכרי he who comes from an unknown country, and is himself unknown (vid., under Proverbs 26:24); the idea of both words, however, passes from advena and alienigena to alius. There is certainly in rare cases a praising of oneself, which is authorized because it is demanded (2-Corinthians 11:18), which, because it is offered strongly against one's will, will be measured by truth (Proverbs 10:13); but in general it is improper to applaud oneself, because it is a vain looking at oneself in a glass; it is indecent, because it places others in the shade; imprudent, because it is of no use to us, but only injures, for propria laus sordet, and as Stobus says, οὐδὲν οὕτως ἄκουσμα φορτικὸν ὡς καθ ̓ αὑτοῦ ἔταινος. Compare the German proverb, "Eigenlob stinkt, Freundes Lob hinkt, fremdes Lob klingt" [= self-praise stinks, a friend's praise is lame, a stranger's praise sounds].