And in the third year, Josaphat king of Juda came down to the king of Israel.

But in the third year, Jehoshaphat, the king of Judah, descended to the king of Israel.

This visit indicates an entire change in the relations which we have hitherto found subsisting between the kingdoms of Israel and Judah. The common danger to which the two kingdoms were exposed from the growing power of Syria had probably induced them to forget their differences. Jehoshaphat's eldest son, Jehoram, was married to Athaliah, the daughter of Ahab: but apparently the bond between the two families had not hitherto led to any very close intimacy, much less to any joint military expeditions. Jehoshaphat seems to have taken no part in the former Syrian wars of Ahab, nor did he join in the great league against the Assyrians (1-Kings 22:1 note). His visit now was probably one of mere friendliness, without any political object. Ahab, however, turned the visit to political advantage. From this time until the displacement of Ahab's dynasty by Jehu, very intimate relations subsisted between the two kingdoms (1-Kings 22:49; 2-Kings 3:7; 2-Kings 8:28-29; 2-Chronicles 20:36, etc.).

And it came to pass in the third year, that Jehoshaphat the king of Judah (b) came down to the king of Israel.
(b) To see and visit him.

And it came to pass in the third year,.... Of the peace, before it was expired:
that Jehoshaphat the king of Judah came down to the king of Israel; to Ahab, from Jerusalem to Samaria, reckoned thirty two miles (m); either to make peace with him, and put an end to the wars which subsisted between Israel and Judah since the division of the kingdom, 1-Kings 22:44 or to contract an affinity with him, by marrying his son to a daughter of Ahab, 2-Kings 8:18 or rather after peace was made, and that strengthened by the marriage; and so he went merely to pay a visit, as he judged he might then with great safety; and he and all his retinue were entertained by Ahab in a very sumptuous and liberal manner, 2-Chronicles 18:1.
(m) Bunting's Travels, &c. p. 178. near 40, Rainold. Praelect. 31. col. 266.

Jehoshaphat the king of Judah came down to the king of Israel--It was singular that a friendly league between the sovereigns of Israel and Judah should, for the first time, have been formed by princes of such opposite characters--the one pious, the other wicked. Neither this league nor the matrimonial alliance by which the union of the royal families was more closely cemented, met the Lord's approval (2-Chronicles 19:2). It led, however, to a visit by Jehoshaphat, whose reception in Samaria was distinguished by the most lavish hospitality (2-Chronicles 18:2). The opportunity of this visit was taken advantage of, to push an object on which Ahab's heart was much set.

Came down, &c. - It is strange, that so good a man would be so closely connected with a king revolted from the worship of God! But he appears to have been of too easy a temper, which betrayed him to many inconveniencies.