In the days of Jehoram, Edom rebelled against the hand of Judah and appointed their own king.
Jehoshaphat secured the kingdom to his firstborn out of paternal kindness, portioning his better brothers so they would not trouble him, but indulgence breeds ingratitude, not duty. Whether he served his people well by putting an unfit man on the throne when others were hopeful and wise, I cannot say; the welfare of the people must be the first law.
AI summary
Commenting on 2 Chronicles 21:1-11
EDOM AND LIBNAH REVOLT. (Ch2 21:8-17) the Edomites revolted--That nation had been made dependent by David, and down to the time of Jehoshaphat was governed by a tributary ruler (Kg1 22:47; Kg2 3:9). But that king having been slain in an insurrection at home, his successor thought to ingratiate himself with his new subjects by raising the flag of independence [JOSEPHUS].
In his days the Edomites revolted - See on Kg2 8:21 (note).