2 Chronicles 30:15
Then they killed the passover on the fourteenth day of the second month: and the priests and the Levites were ashamed, and sanctified themselves, and brought in the burnt offerings into the house of the LORD. Then they killed the passover on the fourteenth day of the second month: and the priests and the Levites were ashamed, and sanctified themselves, and brought in the burnt offerings into the house of the LORD.
The killing of the Passover on the fourteenth day of the second month was the first Passover of Hezekiah's reform. It came nearly a century before the reformation in the eighteenth year of Josiah. That later reformation provided for teaching priests to read the book of the law publicly to the people daily. The Passover under Hezekiah was kept with renewed attention to the law of Moses.
The prosperity of Hezekiah's reign grew out of observance of the statutes recorded by Moses. Those statutes had already helped make his reign prosperous at the time of this Passover. Chief among them were those given in the book of the covenant, which forms a part of Deuteronomy.