Malachi 4:4-6

4 "Remember the law of Moses my servant, which I commanded to him in Horeb for all Israel, even statutes and ordinances.  5 Behold, I will send you Elijah the prophet before the great and terrible day of Yahweh comes.  6 He will turn the hearts of the fathers to the children, and the hearts of the children to their fathers, lest I come and strike the earth with a curse."