Adam Clarke's Bible Commentary Verse 6. He had the daughter of Ahab to wife] This was Athaliah, daughter of Ahab and Jezebel, who was famous for her impieties and cruelty, as was her most profligate mother. It is likely that she was the principal cause of Jehoram's cruelty and profaneness.
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 וילך1980 בדרך1870 מלכי4428 ישׂראל3478 כאשׁר834 עשׂו6213 בית1004 אחאב256 כי3588 בת1323 אחאב256 היתה1961 לו אשׁה802 ויעשׂ6213 הרע7451 בעיני5869 יהוה׃3068