Charles Ellicott Commentary 2 Chronicles 35:22

"Nevertheless Josiah would not turn his face from him, but disguised himself, that he might fight with him, and hearkened not unto the words of Neco from the mouth of God, and came to fight in the valley of Megiddo." — 2 Chronicles 35:22 (ASV)

But disguised himself. —Like Ahab (2 Chronicles 18:29). The Septuagint reads, he strengthened himself, or persisted (ἐκραταιώθη). (Compare to 3 Esdras 1:28.) This implies the reading hithchazzaq instead of hithchappêsh. It is wholly unlikely that disguised himself is used in the figurative sense of “departed from his true character,” as Keil and Zöckler think.

The words of Necho from the mouth of God. —The warning of Necho was really divine, as the event proved. For words of Necho, 3 Esdras 1:26 has, words of the prophet Jeremiah; but there is no trace of such a warning in the extant prophecies bearing his name.

In the valley of Megiddo. —The valley of the Kishon, where Deborah and Barak had fought in ancient times against Jabin and Sisera. Herodotus (ii. 159) calls the place Magdolus. (See on 2 Kings 23:29.)