Albert Barnes 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)

Disguised himself - Compare the marginal reference. But most modern critics are dissatisfied with this meaning here and prefer to render it as “equipped himself,” or—following the Septuagint—to adopt another reading and render it as “took courage.”

The words of Necho from the mouth of God - The author apparently regarded Necho’s words as genuinely prophetic: a warning that Josiah should have listened to, sent by God to make him pause. This was true even though the words were not spoken by divine inspiration or as a result of any supernatural revelation of the divine will to the Egyptian king. Compare this to the prophecy of Caiaphas (John 11:51).