'Passover lambs' in the Bible

Then they slaughtered the Passover lambs on the fourteenth of the second month. And the priests and Levites were ashamed of themselves, and consecrated themselves and brought burnt offerings to the house of the Lord.

For there were many in the assembly who had not consecrated themselves; therefore, the Levites were over the slaughter of the Passover lambs for everyone who was unclean, in order to consecrate them to the Lord.