In the word of the Lord - By the word or command of the Lord; that is, God has commanded thee to smite me. Refusing to do it, this man forfeited his life, as we are informed in the next verse.
By this emblematical action he intended to inform Ahab that, as the man forfeited his life who refused to smite him when he had the Lord's command to do it; so he (Ahab) had forfeited his life, because he did not smite Ben-hadad when he had him in his power.
The sons of the prophets - The expression occurs here for the first time. It signifies (marginal references), the schools or colleges of prophets which existed in several of the Israelite, and probably of the Jewish, towns, where young men were regularly educated for the prophetical office. These “schools” make their first appearance under Samuel 1 Samuel 19:20. There is no distinct evidence that they continued later than the time of Elisha; but it is on the whole most probable that the institution survived the captivity, and that the bulk of the “prophets,” whose works have come down to us belonged to them. Amos Amos 7:14-15 seems to speak as if his were an exceptional case.
Said unto his neighbor - Rather, “to his friend” or “companion “ - to one who was, like himself, “a prophet‘s son,” and who ought therefore to have perceived that his colleague spoke “in the word of the Lord.”