Numbers 18:2

Overview - Numbers 18
The charge of the priests and Levites.
The priests' portion.
21 The Levites' portion.
25 The heave offering to the priests out of the Levites' portion.
Treasury of Scripture Knowledge

Numbers 18:2  (King James Version)
And thy brethren also of the tribe of Levi, the tribe of thy father, bring thou with thee, that they may be joined unto thee, and minister unto thee: but thou and thy sons with thee shall minister before the tabernacle of witness.

joined unto thee
There is a fine paronomasia in the original. Levi is desired from {lawah,} to join, couple, associate; hence Moses says, the Levites {yillawoo,} "shall be joined," or associated, with the priests: they shall conjointly perform the sacred office, but the priests shall be principal, the Levites their associates or assistants.
4 ; Genesis 29:34

3:6-9 Numbers 8:19 Numbers 8:22

but thou
3:10-13 4:15 16:40 17:7 1 Chronicles 16:39 1 Chronicles 16:40 ; 2 Chronicles 30:16 ; Ezekiel 44:15