This man had sent letters in his own name, not in Yahweh"s name, to Zephaniah ben Maaseiah the priest, the other priests, and the people in Jerusalem. He had told them that the Lord wanted Zephaniah to be the priest in charge of order in the temple instead of Jehoiada, the authorized priest. [1] Zephaniah was to put any "mad man" who prophesied in the Lord"s name in the stocks and his neck in an iron collar (cf. Jeremiah 20:1-3). The Hebrew word translated "iron collar" occurs only here in the Old Testament. Its meaning is somewhat obscure, though it probably describes some type of restraining device. [source][source][source]
"The irony is that Zephaniah would, according to Deuteronomy 28:34, become a madman himself when he witnessed the judgment coming upon Jerusalem." [2][source]