Proverbs 30:32

If thou hast done foolishly in lifting up thyself, or if thou hast thought evil, lay thine hand upon thy mouth.

The saying belongs to the words of Agur, regarded as a later portion of the book of Proverbs. If self-exaltation has led to foolish action, or an evil thought has been entertained, the required course is humble silence and restraint of the tongue. Pride and evil thinking must not be permitted to produce harmful and hurtful words, but speech must be stopped and the tongue held.

The figure is that of placing the hand over the mouth to keep a recognized evil thought from breaking out into improper speech. Meek acceptance of reproof assists in that restraint, preventing inward evil from becoming outward words. The same restraint applies to grumbling, so that when others are enduring serious suffering one's own troubles are to be seen as comparatively light and complaint is to cease.