Malachi Chapter Two - Divorce and Tithing

In the beginning of chapter two, malachi has a conversation with the priests. Their job in the old testament was not just to offer the sacrifices in the temple, but to teach the people too. They didn't think it was worth putting in the effort to really understand god's word and to teach it in a way that was clear. So because of the way they've treated him, he will treat them like the dung from the animal sacrifices - which is supposed to be thrown on a rubbish heap.