Numbers 8:8
Then let them take a young bullock with his meat offering, even fine flour mingled with oil, and another young bullock shalt thou take for a sin offering. Then let them take a young bullock with his meat offering, even fine flour mingled with oil, and another young bullock shalt thou take for a sin offering.
The verse stands within the directions given for making the Levites clean for service. Its setting is a rite of purification rather than any other part of their appointment. Those to be purified under these directions are the Levites.