2 Chronicles 29:15-17

15When they had assembled their brothers and consecrated themselves, they went in to cleanse the house of the LORD, according to the command of the king by the words of the LORD.

16So the priests went inside the house of the LORD to cleanse it, and they brought out to the courtyard all the unclean things that they found in the temple of the LORD. Then the Levites took these things and carried them out to the Kidron Valley. 17They began the consecration on the first day of the first month, and on the eighth day of the month they reached the portico of the LORD. For eight more days they consecrated the house of the LORD itself, finishing on the sixteenth day of the first month.