Levites: Subordinate to the Sons of Aaron
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Numbers 3:9
Assign the Levites to Aaron and his sons; they have been given exclusively to him from among the Israelites.
Numbers 8:19
And I have given the Levites as a gift to Aaron and his sons from among the Israelites, to perform the service for the Israelites at the Tent of Meeting and to make atonement on their behalf, so that no plague will come against the Israelites when they approach the sanctuary.”
Numbers 18:6
Behold, I Myself have selected your fellow Levites from the Israelites as a gift to you, dedicated to the LORD to perform the service for the Tent of Meeting.