Numbers 18:2-4

WEB_Strongs(i)
  2 H251 Your brothers H4294 also, the tribe H3878 of Levi, H4294 the tribe H1 of your father, H7126 bring H3867 near with you, that they may be joined H8334 to you, and minister H1121 to you: but you and your sons H6440 with you shall be before H168 the tent H5715 of the testimony.
  3 H8104 They shall keep H4931 your commands, H4931 and the duty H168 of all the Tent: H7126 only they shall not come near H3627 to the vessels H6944 of the sanctuary H4196 and to the altar, H4191 that they not die, neither they, nor you.
  4 H3867 They shall be joined H8104 to you, and keep H4931 the responsibility H168 of the Tent H4150 of Meeting, H5656 for all the service H168 of the Tent: H2114 and a stranger H7126 shall not come near to you.