2 Chronicles 29:15-17

15And they gathered their brethren, and sanctified themselves, and came, according to the commandment of the king, by the words of Yhwh, to cleanse the house of Yhwh.1

16And the priests went into the inner part of the house of Yhwh, to cleanse it, and brought out all the uncleanness that they found in the temple of Yhwh into the court of the house of Yhwh. 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 Yhwh: so they sanctified the house of Yhwh in eight days; and in the sixteenth day of the first month they made an end.