Leviticus 23:8

But ye 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 ,

in the seventh day is an holy convocation, ye 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 .