After that, the Levites came to do their work at the tent of meeting under the supervision of Aaron and his sons. They did with the Levites just as the LORD commanded Moses.
NIV
And after that the Levites went in to do their service in the Tent of Meeting with the attendance of Aaron and his sons; as the Lord had commanded Moses concerning the Levites, so did they to them.
AMP
And after that went the Levites in to do their service in the tabernacle of the congregation before Aaron, and before his sons: as the LORD had commanded Moses concerning the Levites, so did they unto them.
KJV
"They may assist their brothers in performing their duties at the tent of meeting, but they themselves must not do the work. This, then, is how you are to assign the responsibilities of the Levites."
NIV
But shall help their brethren in the Tent of Meeting [attend to protecting the sacred things from being profaned], but shall do no regular or heavy service. Thus shall you direct the Levites in regard to their duties.
AMP
But shall minister with their brethren in the tabernacle of the congregation, to keep the charge, and shall do no service. Thus shalt thou do unto the Levites touching their charge.
KJV