Deuteronomy 8:3; Deuteronomy 23:23

Deuteronomy 8:3

3 "He humbled you and let you be hungry, and fed you with manna which you did not know, nor did your fathers know, that He might make you understand that man does not live by bread alone, but man lives by everything that proceeds out of the mouth of the LORD .

Deuteronomy 23:23

23 "You shall be careful to perform what goes out from your lips, just as you have voluntarily vowed to the LORD your God, what you have promised.