Jamieson, Fausset and Brown on 2 Kings 10:19

19. call unto me all the prophets of Baal--The votaries of Baal are here classified under the several titles of prophets, priests, and servants, or worshippers generally. They might be easily convened into one spacious temple, as their number had been greatly diminished both by the influential ministrations of Elijah and Elisha, and also from the late King Joram's neglect and discontinuance of the worship. Jehu's appointment of a solemn sacrifice in honor of Baal, and a summons to all his worshippers to join in its celebration, was a deep-laid plot, which he had resolved upon for their extinction, a measure in perfect harmony with the Mosaic law, and worthy of a constitutional king of Israel. It was done, however, not from religious, but purely political motives, because he believed that the existence and interests of the Baalites were inseparably bound up with the dynasty of Ahab and because he hoped that by their extermination he would secure the attachment of the far larger and more influential party who worshipped God in Israel. Jehonadab's concurrence must have been given in the belief of his being actuated solely by the highest principles of piety and zeal.