Proverbs 27:2 Kabbalah

יְהַלֶּלְךָ֣ זָ֣ר וְלֹא־פִ֑יךָ נָ֝כְרִ֗י וְאַל־שְׂפָתֶֽיךָ׃

Let another man praise thee, and not thine own mouth; A stranger, and not thine own lips.

Read kabbalistic (mystical) interpretation of Proverbs 27:2: and classical mystical sources.