Exodus 20:7 "You shall not take the name of Yahweh your God in vain, for Yahweh will not hold him guiltless who takes his name in vain. (See NIV)
Deuteronomy 5:11 "You shall not take the name of Yahweh your God in vain: for Yahweh will not hold him guiltless who takes his name in vain. (See NIV)