John Gill Commentary Leviticus 23:8

"But ye shall offer an offering made by fire unto Jehovah seven days: in the seventh day is a holy convocation; ye shall do no servile work." — Leviticus 23:8 (ASV)

But you shall offer an offering made by, fire unto the Lord
seven days
A burnt offering was to be offered unto the Lord on everyone of the seven days, which were two young bullocks, one ram, and seven lambs; besides a meat offering, and a goat for a sin offering, (Numbers 28:19–24); in the seventh day is an holy convocation, you shall do no servile
work therein ;
as on the first day, that was on account of the Israelites going out of Egypt; and this is said, on account of Pharaoh and his host being drowned on it; (See Gill on Exodus 12:16).