Charles Ellicott Commentary Proverbs 30:32

"If thou hast done foolishly in lifting up thyself, Or if thou hast thought evil, [Lay] thy hand upon thy mouth." — Proverbs 30:32 (ASV)

Lay thine hand upon thy mouth: that is, be silent. Agur deprecates two things which may easily lead to a quarrel, arrogance and malice. He explains this in the next verse.