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.
KJV
For [there were] many in the congregation that were not sanctified: therefore the Levites had the charge of the killing of the passovers for every one [that was] not clean, to sanctify [them] unto the LORD.
ASV
For there were many in the assembly that had not sanctified themselves: therefore the Levites had the charge of killing the passovers for every one that was not clean, to sanctify them unto Jehovah.