Cross reference
2 Chronicles 30:3
3 For they could not keep it at that time, because the priests had not sanctified themselves in sufficient number, neither had the people gathered themselves together to Jerusalem.
2 Chronicles 29:34
34 But the priests were too few, so that they could not flay all the burnt-offerings: wherefore their brethren the Levites did help them, till the work was ended, and until the priests had sanctified themselves; for the Levites were more upright in heart to sanctify themselves than the priests.
Exodus 12:6
6 and ye shall keep it until the fourteenth day of the same month; and the whole assembly of the congregation of Israel shall kill it at even.
Exodus 12:18
18 In the first `month', on the fourteenth day of the month at even, ye shall eat unleavened bread, until the one and twentieth day of the month at even.
2 Chronicles 29:17
17 Now 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 Jehovah; and they sanctified the house of Jehovah in eight days: and on the sixteenth day of the first month they made an end.