Numbers 18:7

shall keep your priesthood i.e. perform its distinctive duties.

within the veil viz. the first hanging, at the entrance to the Holy Place. The Levites were debarred from entering any part of the tent, and from contact with the altar of burnt-offering in the court.

as a service of gift The expression (if the text be correct) emphasizes the fact that the priests had done nothing to deservethese privileges; they were a free gift. The LXX. suggest a different reading -Ye shall perform the acts of service (as a) gift of your priesthood"; but the meaning is substantially the same. S. Paul gives similar teaching with regard to Christian privileges, 1 Corinthians 4:7.