2 Chronicles 29:15-17

15They gathered their brothers (fellow Levites) together, consecrated themselves, and went in to cleanse the house of the Lord, as the king had commanded by the words of the Lord.

16The priests went into the inner part of the house of the Lord to cleanse it, and every unclean thing they found in the temple of the Lord they brought out to the courtyard of the Lord’s house. Then the Levites received it to take out to the Kidron Valley [for disposal].

17Now they began the consecration on the first [day] of the first month, and on the eighth day of the month they came to the porch of the Lord. Then for eight days they consecrated the house of the Lord, and on the sixteenth day of the first month they finished.