Charles Ellicott Commentary Leviticus 17:1

"And Jehovah spake unto Moses, saying," — Leviticus 17:1 (ASV)

And the Lord spoke to Moses. —The Day of Atonement was instituted to purge, in a special manner, the whole community from all their sins, and present them a holy nation before the Lord once a year. Hence it is now followed by regulations concerning everyday life, the observance of which is to foster the holiness secured on that particular day.