2 Chronicles 29:16-17

16And the priests went into the inner part of the house of the Lord, to cleanse it, and brought out all the uncleanness that they found in the temple of the Lord into the court of the house of the Lord. And the Levites took it, to carry it out abroad into the brook Kidron.

17Now they began on the first day of the first month to sanctify, and on the eighth day of the month came they to the porch of the Lord: so they sanctified the house of the Lord in eight days; and in the sixteenth day of the first month they made an end.