The sentence that begins "Then Yahweh spoke to Moses, saying" (verse 8) has a quotation within a quotation. A direct quotation can be stated as an indirect quotation. "Then Yahweh spoke to Moses and told him to command Aaron and his sons, saying, 'This is the law" (See:[[rc://en/ta/man/jit/figs-quotesinquotes]] and [[rc://en/ta/man/jit/figs-quotations]])
This can be translated in active form. Alternate translation: "you must keep the fire of the altar burning" (See: [[rc://en/ta/man/jit/figs-activepassive]])