With the understanding that the hearts of the fathers are turned to their children and the hearts of the children are turned to their fathers, there are two possibilities. The fathers
and children
could refer literally to the fathers and children in one household, and then specifically to the children who become estranged from their fathers who chose to divorce their faithful wives and marry pagan women (Malachi 2:11–14).
But there is a preferred option, namely, that the fathers
refers to the patriarchs,
and that the children refer to the Israelites of later generations.
6 And he will turn the hearts of fathers to their children and the hearts of children to their fathers, lest I come and strike the land with a decree of utter destruction.”