Malachi 4:4-6

Remember ye the law of Moses my servant, which I commanded unto him in Horeb for all Israel, with the statutes and judgments. Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the LORD: and he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse.