Charles Ellicott Commentary Numbers 4:18

"Cut ye not off the tribe of the families of the Kohathites from among the Levites;" — Numbers 4:18 (ASV)

Cut ye not off the tribe ... — The word shebet (tribe) is used here in a very particular sense and denotes only one division of the tribe of Levi. In this and the following verses, the injunction already given (Numbers 5:15) is renewed, and Moses and Aaron are charged not to be guilty of such negligence regarding it as might expose the Kohathites to death as a result of their unlawful treatment of the holy things. Moses and Aaron might be said to do what would be the result of their negligence.

In like manner, St. Paul enjoins the Roman Christians in these words: “Destroy not him with thy meat for whom Christ died” (Romans 14:15).