but no man can tame the tongue. It is a restless evil, full of deadly poison.
The foregoing chapter shows how unprofitable and dead faith is without works. It is plainly intimated by what this chapter first goes upon that such a faith is, however, apt to make men conceited and magisterial in their tempers and their talk. Those who set up faith in the manner the former chapter condemns are most apt to run into those sins of the tongue which this chapter condemns.
Commenting on James 3:1-12
But the tongue can no man tame,.... Either his own, or others; not his own, for the man that has the greatest guard upon himself, his words and actions; yet, what through pride or passion, or one lust or another in his heart, at one time or another, bolts out vain, idle, angry, and sinful words: and he that does not may be set down...
Verse 8. But the tongue can no man tame. This does not mean that it is never brought under control, but that it is impossible effectually and certainly to subdue it. It would be possible to subdue and domesticate any kind of beasts, but this could not be done with the tongue, It is an unruly evil. An evil without restraint, to which no certain effectual check can be applied.