15 And they gathered their brethren, and they purified themselves according to the king's command by the order of the Lord, to purify the house of the Lord.
2 Chronicles 29:15 Cross References - CAB
1 Chronicles 23:28
28 For he appointed them to wait on Aaron, to minister in the house of the Lord, over the courts, and over the chambers, and over the purification of all the holy things, and over the works of the service of the house of God;
2 Chronicles 29:5
5 and said to them, Hear, you Levites: Now sanctify yourselves, and sanctify the house of the Lord God of your fathers, and cast out the impurity from the holy places.
2 Chronicles 30:12
12 And the hand of the Lord was present to give them one heart to come, to do according to the commands of the king and of the princes, by the word of the Lord.