the Levites
2 Chronicles 29:34
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 other priests had sanctified themselves: for the Levites were more upright in heart to sanctify themselves than the priests.
2 Chronicles 35:3-6
3
And said unto the Levites that taught all Israel, which were holy unto the LORD, Put the holy ark in the house which Solomon the son of David king of Israel did build; it shall not be a burden upon your shoulders: serve now the LORD your God, and his people Israel,
4
And prepare yourselves by the houses of your fathers, after your courses, according to the writing of David king of Israel, and according to the writing of Solomon his son.
5
And stand in the holy place according to the divisions of the families of the fathers of your brethren the people, and after the division of the families of the Levites.
6
So kill the passover, and sanctify yourselves, and prepare your brethren, that they may do according to the word of the LORD by the hand of Moses.
the killing
Exodus 12:6
And ye shall keep it up until the fourteenth day of the same month: and the whole assembly of the congregation of Israel shall kill it in the evening.