Barnes New Testament Notes

Verse 3. Behold, we put bits in the horses' mouths, etc. The meaning of this simple illustration is, that as we control a horse by the bit -- though the bit is a small thing -- so the body is controlled by the tongue. He who has a proper control over his tongue can govern his whole body, as he who holds a bridle governs and turns about the horse.

{a} "we put bits in the horses' mouths" Ps 32:9