Deuteronomy 29:18-20

18Make sure there is no man or woman, clan or tribe among you today whose heart turns away from the Lord our God to go and worship the gods of those nations; make sure there is no root among you that produces such bitter poison. 19When such a person hears the words of this oath and they invoke a blessing on themselves, thinking, “I will be safe, even though I persist in going my own way,” they will bring disaster on the watered land as well as the dry. 20The Lord will never be willing to forgive them; his wrath and zeal will burn against them. All the curses written in this book will fall on them, and the Lord will blot out their names from under heaven.