Malachi 4:4-6

4“Remember the law of my servant Moses, the decrees and laws I gave him at Horeb for all Israel. 5“See, I will send the prophet Elijah to you before that great and dreadful day of the LORD comes. 6He will turn the hearts of the parents to their children, and the hearts of the children to their parents; or else I will come and strike the land with total destruction.”