And you shall appoint Aaron and his sons, and they shall attend to their priesthood: The point of this whole verse is that only Aaron and his sons will be priests, and nobody else. This is clearly implied in the Hebrew construction of this sentence, which is literally “And Aaron and his sons [that is, nobody else] you shall appoint, and they shall keep their priesthood.” New Revised Standard Version renders the first clause of this verse as “But you shall make a register of Aaron and his descendants.” The Hebrew verb rendered appoint (paqad) is the same one translated “number” in 1.3 (see the comments there). But here there are only three people (Aaron and his two remaining sons) that Moses needs to enroll. There are no other “descendants” yet. This verb can also mean “appoint, entrust with an official duty, assign” (The Hebrew and Aramaic Lexicon of the Old Testament, volume 3, page 956), which is the sense it has here. New Revised Standard Version renders this verb as “assign” in 4.32. Good News Translation renders and they shall attend to their priesthood as “to carry out the duties of the priesthood,” which may be an easier model to follow. A good model for this whole sentence is “But you shall appoint [only] Aaron and his sons; it is they [alone] who shall perform the duties of [my] priests.”

But if any one else comes near is literally “and the stranger/foreigner/outsider who approaches/encroaches.” See the comments on 1.51. The conjunction but may be needed in some languages to indicate the contrastive warning that follows. Good News Translation indicates this break in thought by not using any conjunction. Good News Translation renders this clause as “anyone else who tries to do so,” which means “anyone else who tries to be a priest.” Particularly after the brief story about Nadab and Abihu in verse 4 and in line with 1.51, it is also accurate to say “any lay person who encroaches on it” (similarly New Jewish Publication Society’s Tanakh, Milgrom). New International Version says “anyone else who approaches the sanctuary,” but this rendering may imply that even the Levites are intruders.

He shall be put to death: See 1.51.

Quoted with permission from de Regt, Lénart J. and Wendland, Ernst R. A Handbook on Numbers. (UBS Helps for Translators). Miami: UBS, 2016. For this and other handbooks for translators see here .