When you make a promise to God, don't fail to keep it, since he isn't pleased with fools. Keep what you promise

If thou promise anything, pay it; for better it is that thou make no vow than that thou shouldest promise, and not pay.

Never let your mouth cause you to sin and don't proclaim in the presence of the angel, "My promise was a mistake," for why should God be angry at your excuse and destroy what you've undertaken?