Finally, Josiah is killed by Pharaoh, the king of Egypt, because he would not listen to the words of the Lord from the mouth of the prophet Jeremiah, or, as it is written in the Paralipomenon: "Josiah would not return but prepared to fight against him and did not listen to the words of Neco from the mouth of God." And it is stated, "And he died and was buried in the monument of his ancestors. And all Judah and Jerusalem mourned for him, particularly Jeremiah, whose lamentations for Josiah all the singing men and singing women repeat to this day. And it became like a law in Israel: 'Behold, it is found written in the Lamentations.' "
Source: Against the Pelagians 2.22