Numbers 8:19 NIrV

[19] I have given the Levites as gifts to Aaron and his sons. I have taken them from among all the Israelites. I have appointed them to do the work at the tent of meeting. They will do it in place of the Israelites. That is how they will keep the Israelites from being guilty when they go near the sacred tent. Then no plague will strike the Israelites when they go near the tent.”