We arrive to the close of Jehoshaphat's reign and life together. The length of it was not equal to many of the kings of Judah, though such honourable testimony is given of him. Perhaps the records concerning him, said here to be in the writings of the book of Jehu, might have been extant for a long space after his death; but not being of sacred authority, they were not made a part of the Canon of Scripture.
2 Chronicles 20:31-34
31 And Jehoshaphat reigned over Judah: he was thirty and five years old when he began to reign, and he reigned twenty and five years in Jerusalem. And his mother's name was Azubah the daughter of Shilhi.
32 And he walked in the way of Asa his father, and departed not from it, doing that which was right in the sight of the LORD.
33 Howbeit the high places were not taken away: for as yet the people had not prepared their hearts unto the God of their fathers.
34 Now the rest of the acts of Jehoshaphat, first and last, behold, they are written in the book of Jehug the son of Hanani, who is mentioned in the book of the kings of Israel.