To 'strike hands' and become surety was to pledge to repay someone else's debt if they could not. Proverbs repeatedly warns against this practice (see also 6:1–5; 11:15; 22:26–27) because it puts oneself at financial and relational risk for another's obligation. Doing this carelessly — especially for a friend, where emotional pressure is highest — marks a person as lacking good judgment.
Memory phrase: Think before you promise.
Talk about it: Why is making promises you cannot keep unwise?
Prayer: God, help me think carefully before I promise.