Numbers 18:2-4

CKJV_Strongs(i)
  2 H251 And your brothers H4294 also of the tribe H3878 of Levi, H7626 the tribe H1 of your father, H7126 bring H3867 you with you, that they may be joined H8334 unto you, and minister H1121 unto you: but you and your sons H6440 with you shall minister before H168 the tabernacle H5715 of witness.
  3 H8104 And they shall keep H4931 your charge, H4931 and the charge H168 of all the tabernacle: H7126 only they shall not come near H3627 the vessels H6944 of the sanctuary H4196 and the altar, H4191 that neither they, nor you also, die.
  4 H3867 And they shall be joined H8104 unto you, and keep H4931 the charge H168 of the tabernacle H4150 of the congregation, H5656 for all the service H168 of the tabernacle: H2114 and a stranger H7126 shall not come near unto you.