Charles Ellicott Commentary Psalms 32:9

"Be ye not as the horse, or as the mule, which have no understanding; Whose trappings must be bit and bridle to hold them in, [Else] they will not come near unto thee." — Psalms 32:9 (ASV)

Whose mouth. — Here the text has evidently suffered, and the exact meaning is lost. There are also verbal difficulties. The word translated “mouth” elsewhere (except Psalm 103:5, where see Note) means “ornament,” and the literal rendering of the text as it stands is, with bit and bridle his ornament to hold, not approaching to you.

This may mean that the animal is harnessed, either “that it may not approach,” or “because without harness it will not approach.” In either case, the general application is the same. Horses and mules can only be rendered obedient by restraints that are unworthy of a rational creature.

The Septuagint and Vulgate have “jaws” instead of “mouth,” and Ewald follows them, and renders the last clause, ‘of those who approach you unfriendly.’