Leviticus 27:7

And thy estimation shall be of the male from twenty years old even unto sixty years old, even thy estimation shall be fifty shekels of silver, after the shekel of the sanctuary.

So Abijah slept with his fathers, and they buried him in the city of David: and Asa his son reigned in his stead. In his days the land was quiet ten years.

And there was no more war unto the five and thirtieth year of the reign of Asa.

And Asa in the thirty and ninth year of his reign was diseased in his feet, until his disease was exceeding great: yet in his disease he sought not to the LORD, but to the physicians.

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.

Amaziah was twenty and five years old when he began to reign, and he reigned twenty and nine years in Jerusalem. And his mother's name was Jehoaddan of Jerusalem.

And Amaziah the son of Joash king of Judah lived after the death of Joash son of Jehoahaz king of Israel fifteen years.

Moreover Amaziah gathered Judah together, and made them captains over thousands, and captains over hundreds, according to the houses of their fathers, throughout all Judah and Benjamin: and he numbered them from twenty years old and above, and found them three hundred thousand choice men, able to go forth to war, that could handle spear and shield.