Numbers 4:18-20

Young's Literal Translation

¹⁸ `Ye do not cut off the tribe of the families of the Kohathite from the midst of the Levites;

¹⁹ but this do to them, and they have lived, and do not die in their drawing nigh the holy of holies: -- Aaron and his sons go in, and have set them, each man to his service, and unto his burden,

²⁰ and they go not in to see when the holy thing is swallowed, that they have died.'