Notes on the Bible, by Albert Barnes, , at sacred-texts.com
2 Chronicles 21:1
Jehoram's sole reign now began. (See Kg2 8:16 note). His eight years Ch2 21:5 must be counted from the time of his association, in his father's 23rd year.
2 Chronicles 21:3
Jehoshaphat departed from Rehoboam's policy (Ch2 11:23 note), actually making over to his sons the "fenced cities" in which they dwelt. This, it is probable, provoked the jealousy of Jehoram, and induced him to put them to death Ch2 21:4.
Because he was the firstborn - Compare Deu 21:15-17. Exceptions to this rule in the northern and southern kingdoms are Solomon, where divine appointment superseded the natural order, Abijah Ch2 11:22 note), and Jehoahaz (Kg2 23:30 note).
2 Chronicles 21:4
The execution of several "princes of Israel" (i. e. of Judah; see Ch2 20:34 note) implies that Jehoram's brothers found supporters among the chief men of the country, and that Jehoram's sole sovereignty was not established without a struggle.
2 Chronicles 21:11
See Kg2 8:18. The writer of Kings only tells us in general terms that Jehoram "did evil in the sight of the Lord," and "walked in the way of the house of Ahab." Here, in Ch2 21:11, Ch2 21:13, we have particulars of his idolatry. Jehoram, it seems, seduced by the evil influence of his wife - Athaliah, the daughter of Ahab - permitted the introduction of Baal-worship, idolatrous altars in various high places, groves (Asherahs), images, and pillars; the people were not only allowed, but compelled to take part in the new rites. "To commit fornication" is a common metaphor, signifying idolatry or spiritual unfaithfulness (compare the Kg2 9:22 note).
2 Chronicles 21:12
This is the only notice which we have of Elijah in Chronicles. As a prophet of the northern kingdom, he engaged but slightly the attention of the historian of the southern one. The notice shows that Elijah did not confine his attention to the affairs of his own state, but strove to check the progress of idolatry in Judah. And it proves that he was alive after the death of Jehoshaphat Ch2 21:13; a fact bearing
(1) upon the chronological order of Kg2 2:1 (see the note), and
(2) showing that Elisha, who prophesied in the time of Jehoshaphat. Kg2 3:11-19 commenced his public ministry before his master's translation.
2 Chronicles 21:14
The fulfillment of the threat is given in Ch2 21:16-17.
2 Chronicles 21:16
The Arabians, that were near the Ethiopians - Probably Joktanian Arabs from the neighborhood of the Cushites. Southern Arabia was originally occupied by Cushites, or Ethiopians Gen 10:7, whose descendants still exist in a remnant of the Himyaritic Arabs.
2 Chronicles 21:17
Jehoahaz - The writer of Chronicles calls him indifferently Jeboahaz and Abaziah, which are equivalent names (Kg2 8:24 note).
2 Chronicles 21:20
Not in the sepulchres of the kings - Compare the similar treatment of Joash Ch2 24:25 and Ahaz Ch2 28:27.