John Gill Commentary 2 Chronicles 19

And Jehoshaphat the king of Judah returned
From Ramothgilead, after Ahab was slain:

to his house in peace in Jerusalem ;
to his palace there in safety, having narrowly escaped losing his life in the battle.

And Jehu the son of Hanani the seer
The son of him that reproved Asa, for which he put him in prison, (2 Chronicles 17:7 2 Chronicles 17:10) , but that did not deter this his son from reproving Jehoshaphat:

went out to meet him ;
as he was returning:

and said to King Jehoshaphat, should you help the ungodly ;
such an one as Ahab, an idolater, murderer, and persecutor:

and love them that hate the Lord ?
his laws, worship, and ordinances, as he had; intimating, that he had done wrong, by entering into alliance and affinity with him, by showing him friendship, and assisting him in his war against the Syrians:

therefore is wrath upon you from before the Lord ;
which appeared in the war of the Ammonites and Moabites with him, related in the next chapter, and in the calamities that came upon his family, his sons being slain by Jehoram that succeeded him, and his grandsons by Jehu.

Nevertheless, there are good things found in thee
Principles of grace, righteousness, and holiness, faith, love, zeal, and other graces, true and genuine, from which sprung many good works done by him:

in that you have taken away the groves out of the land ;
cut down the groves of trees, and destroyed the idols and images in them:

and have prepared your heart to seek God ;
through the grace of God his heart was disposed to serve and worship the Lord, and to seek his honour and glory.

And Jehoshaphat dwelt at Jerusalem
And went out no more to Samaria, nor concerned himself about the affairs of Israel, but attended to his own:

and he went out again through the people ;
took a tour throughout his dominions now, in his own person, as before by his princes, with the priests and Levites:

from Beersheba to Mount Ephraim ;
Beersheba was the southern boundary of the land of Judah, and Mount Ephraim lay to the north, and was the northern boundary of it since the division of the kingdom:

and brought them back to the Lord God of their fathers ;
from idolatry to the pure worship of God, such who had relapsed since the first reformation, or had not been influenced by it.

And he set judges in the land throughout all the fenced cities
of Judah, city by city
Inferior judges in lesser courts of judicature than that at Jerusalem, and that in every city, that judgment and justice might be executed everywhere; such were appointed by David, but had been neglected, and now restored, see (1 Chronicles 26:29 1 Chronicles 26:32) .