On the Identity of an Anonymous Prophet
I Kings 13:1:
And, behold, a man of God came from Judah to Beth-el by the word of the Lord, and Jeroboam was standing by the altar to offer.
Rashi and other commentators note that the sages (Sanhedrin 89) identify this prophet with Iddo/Jeddo, who, although otherwise absent from the book of Kings, is mentioned explicitly in a number of places in the book of Chronicles, and is perhaps the ancestor of the second prophet Zechariah (Zechariah 1:1). However, this identification can not be taken to be equivocal.
Right before this prophet’s appearance, we read about Jeroboam’s religious innovations (I Kings, 12:31):
He established shrines of high places, and appointed priests from among some of the people – who were not of the sons of Levi.
And after the prophet’s ominous death we find that Jeroboam had not learned his lesson (ibid, 13:33):
After this matter, Jeroboam did not repent of his evil path, but once again appointed from among some of the people priests of the high places; whosoever desired could be initiated into the service and be of the priests of the high places.
That is, originally Jeroboam appointed priests of his own choosing, and included himself, but later he took a more egalitarian approach, opening up his new priesthood to anyone.
Jeroboam and Rehoboam began their reigns simultaneously, and Abijah inherited the Judean throne after Jeroboam had reigned for most of eighteen years. In his short, (almost) three-year reign, he made war with Jeroboam, but before the battle began he delivered a stern rebuke to the ten tribes, admonishing Jeroboam for his innovations, including (II Chronicles 13:9):
Have you not rejected the priests of the Lord, the sons of Aaron and the Levites, and made priests for yourselves as the peoples of other lands [do]? Whoever comes to initiate himself with a young bullock and seven rams, will be a priest to a non-god!
Abijah referred to Jeroboam’s latter reform, which opened the priesthood to all. Yet, when concluding the account of Abijah’s reign, the Chronicler includes (ibid, 22):
And the rest of the acts of Abijah, and his ways and his matters, are written in the commentary of the prophet Iddo.
Thus, because Iddo recorded part of Abijah’s royal history, which included Abijah recounting Jeroboams latter innovations, he could not have been the anonymous prophet who died shortly after chastising Jeroboam for his initial innovations.
From Rabbi Avi Grossman, here.