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: therefore their brothers the Levites helped them, until 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 you shall keep it until the fourteenth day of the same month; and the whole assembly of the congregation of Israel shall kill it at evening.
Exodus 12:18
18 In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, until the twenty first day of the month at evening.
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 Yahweh; and they sanctified the house of Yahweh in eight days: and on the sixteenth day of the first month they made an end.