New Revised Standard Version
They gathered their brothers, sanctified themselves, and went in as the king had commanded, by the words of the LORD, to cleanse the house of the LORD.

Contemporary English Version
These leaders gathered together the rest of the Levites, and they all went through the ceremony to make themselves clean. Then they began to purify the temple according to the Law of the LORD, just as Hezekiah had commanded.

New American Bible
They gathered their kinfolk together and sanctified themselves; then they came as the king had ordered, in keeping with the words of the LORD, to cleanse the LORD’s house.

Douay-Rheims Bible
And they gathered together their brethren, and sanctified themselves, and went in according to the commandment of the king, and the precept of the Lord, to purify the house of God.

And they gathered together their brethren, and sanctified themselves, and went in according to the commandment of the king, and the precept of the Lord, to purify the house of God.

sanctified themselves

2 Chronicles 29:5 And he said to them: Hear me, ye Levites, and be sanctified, purify the house of the Lord the God of your fathers, and take away all filth out of the sanctuary.

by the words of the Lord.

2 Chronicles 30:12 But the hand of God was in Juda, to give them one heart to do the word of the Lord, according to the commandment of the king, and of the princes.

to cleanse

1 Chronicles 23:28 And they are to be under the hand of the sons of Aaron for the service of the house of the Lord, in the porches, and in the chambers, and in the place of purification, and in the sanctuary, and in all the works of the ministry of the temple of the Lord.