And it came to pass on the eighth day, that Moses called Aaron and his sons, and the elders of Israel; On the eighth day - This was the first day after their consecration, before which they were deemed unfit to minister in holy things, being considered as in a state of imperfection. "All creatures," says Ainsworth, "for the most part were in their uncleanness and imperfection seven days, and perfected on the eighth; as children by circumcision, Leviticus 12:2, Leviticus 12:3; young beasts for sacrifice, Leviticus 22:27; persons that were unclean by leprosies, issues, and the like, Leviticus 14:8-10; Leviticus 15:13, Leviticus 15:14; Numbers 6:9, Numbers 6:10. So here, the priests, until the eighth day, were not admitted to minister in their office."
Related Commentaries of Leviticus 9:1
Leviticus 9:1
1 And it came to pass on the eighth day, that Moses called Aaron and his sons, and the elders of Israel;