Adam Clarke's Bible Commentary Verse 8. In his days the Edomites revolted] See on 2 Kings viii. 21.
Matthew Henry Commentary
Verses 1-11 - Jehoram hated his brethren, and slew them, for the same reason tha Cain hated Abel, and slew him, because their piety condemned his impiety. In the mystery of Providence such men sometimes prosper for time; but the Lord has righteous purposes in permitting such events part of which may now be made out, and the rest will be seen hereafter.
Original Hebrew בימיו3117 פשׁע6586 אדום123 מתחת8478 יד3027 יהודה3063 וימליכו4427 עליהם5921 מלך׃4428