The Feast of the Passover: Purification Necessary to the Due Observance of
Source: TTT
2 Chronicles 30:15–19
And on the fourteenth day of the second month they slaughtered the Passover lamb. The priests and Levites were ashamed, and they consecrated themselves and brought burnt offerings to the house of the LORD. / They stood at their prescribed posts, according to the Law of Moses the man of God. The priests sprinkled the blood, which they received from the hand of the Levites. / Since there were many in the assembly who had not consecrated themselves, the Levites were in charge of slaughtering the Passover lambs for every unclean person to consecrate the lambs to the LORD.
John 11:55
Now the Jewish Passover was near, and many people went up from the country to Jerusalem to purify themselves before the Passover.