Midrasch zu Divrej Hajamim II 35:21

“The Lord is righteous, for I have defied His word. Hear now all you peoples, and see my pain: My young women and young men have gone into captivity” (Lamentations 1:18).
“The Lord is righteous, for I have defied His word.” Who said this verse? Yoshiyahu said it. That is what is written: “After all this, when Yoshiyahu had established the House, Nekho king of Egypt came up to wage war at Karkemish on the Euphrates,” (II Chronicles 35:20), Karkasyon on the Euphrates. “[Yoshiyahu went out toward him.] He sent emissaries to him, saying: What is there between me and you, king of Judah? It is not against you today, but against the house with which I have war, and God has said that I should make haste” (II Chronicles 35:20–21). It is by the word of the Holy One blessed be He that I am ascending. “Restrain yourself from god who is with me” (II Chronicles 35:21), this is an expression of idol worship. “Yoshiyahu did not turn his face from him…and did not heed the words of Nekho from the mouth of God” (II Chronicles 35:22), this [alludes to] Jeremiah, who said to Yoshiyahu: ‘So I received from my teacher Isaiah: “I will provoke Egypt against Egypt”’ (Isaiah 19:2). He did not heed him. Rather, he said to him: ‘Did Moses, the teacher of your teacher, not say this: “A sword will not pass in the land” (Leviticus 26:6)? And the sword of that wicked one is passing in my land and my borders.’ But he did not realize that his entire generation was idol worshippers. He would send a pair of students to eradicate idol worship from their houses, but they would enter and not find anything. When they would go out [the residents] would say: ‘Close the doors,’ and when they would close the doors they would see it.²⁰²There were double doors leading into the house. Half the idol was on one door and half on the other. The halves did not look like anything separately, but when the doors were closed, the idol was visible. They would say of them: The one who came to repair is the one who came and ruined.²⁰³Although they divided the idol when they opened the doors, they put it back together when they closed the doors. Therefore: “The archers shot King Yoshiyahu” (II Chronicles 35:23). Rabbi Manei said: They fired three hundred arrows into him until his body became like a sieve. Jeremiah was listening to him to ascertain what he was saying:²⁰⁴He was listening to what Yoshiyahu was saying as he died. What was he saying? “The Lord is righteous, for I have defied His word,” His mouth and the mouth of his agent.

Our Rabbis were taught: Not only does the foregoing apply unto unfriendly armies, but also to peaceful ones [who have no intention of attacking the place, but merely desire to pass through to make war upon others]; for there could not have been a more friendly army than the one which was sent by Pharae N'cho, king of Egypt, to Josiah, king of Judah, and still Josiah lost his life on their account, as it is said (II Chr. 35, 21) But he (Necho, king of Egypt) sent ambassadors to him (Josiah) saying: 'What have I to do with thee, thou king of Judah? I come not against thee this day, but against the house wherewith I have war, and God hath commanded me to make haste: forbear thee from meddling with God who is with me, that He may not destroy thee.' What God could N'cho have had with him? R. Juda said, in the name of Rab: "It was an idol, and for the reason that N'cho had confidence in the idol, Josiah thought that he could surely vanquish him in battle"; And it is written further (Ib. 23) And the archers shot at king Josiah; and the king said to his servants: 'Carry me away; for I am sorely wounded.' What does sorely wounded mean? Said R. Juda, in the name of Rab: "It means that his entire body was perforated by the arrows, like a sieve." Said R. Juda, in the name of Rab: "Why was Josiah punished? Because he did not consult Jeremiah the prophet. When Josiah was dying, Jeremiah the prophet came to visit him and noticed that his lips were moving. Thinking that, God forbid, he was saying something blasphemous on account of the terrible pain he was suffering, Jeremiah bent down and heard Josiah justifying the judgment which had befallen him, reciting the passage (Lam. 1, 18) Righteous is the Lord; for against his orders have I rebelled. Thereupon Jeremiah took up the following text (Ib. 4, 20) The breath of our nostrils, the anointed of our Lord, etc."

3) "and a sword will not pass through your land": Not only will they not come against you for war, but the passers (for war) will not (even) pass from one land (Eretz Yisrael) to the other, as they did in the days of Yoshiyahu (viz. II Chronicles 35:21)