19 Yet the Lord would not destroy Judah for David his servant's sake, as he promised him to give him alway a light,  and to his children.
19 Nevertheless, for the sake of his servant David, the Lord was not willing to destroy Judah. He had promised to maintain a lamp for David and his descendants forever.
19 Yet the Lord was not willing to destroy Judah, for the sake of David his servant, since he promised to give a lamp to him and to his sons forever.
19 But despite that, because of his servant David, God was not ready to destroy Judah. He had, after all, promised to keep a lamp burning through David's descendants.
19 Yet the Lord would not destroy Judah, for the sake of his servant David, as He promised him to give a lamp to him and his sons forever.
19 But the Lord did not want to destroy Judah, for he had promised his servant David that his descendants would continue to rule, shining like a lamp forever.
Matthew Henry's Commentary on 2 Kings 8:19
Commentary on 2 Kings 8:16-24
(Read 2 Kings 8:16-24)
A general idea is given of Jehoram's badness. His father, no doubt, had him taught the true knowledge of the Lord, but did ill to marry him to the daughter of Ahab; no good could come of union with an idolatrous family.