Numbers 18:3 in the King James Version
And they shall keep thy charge, and the charge of all the tabernacle: only they shall not come nigh the vessels of the sanctuary and the altar, that neither they, nor ye also, die.
Context
2 Bring your brothers also, the tribe of Levi, the tribe of your father, near with you, that they may be joined to you, and minister to you; but you and your sons with you shall be before the Tent of the Testimony.
3 They shall keep your commands and the duty of the whole Tent; only they shall not come near to the vessels of the sanctuary and to the altar, that they not die, neither they nor you.
4 They shall be joined to you and keep the responsibility of the Tent of Meeting, for all the service of the Tent. A stranger shall not come near to you.