Numbers 28:16-19

And in the fourteenth day of the first month is the passover of the LORD. And in the fifteenth day of this month is the feast: seven days shall unleavened bread be eaten. In the first day shall be an holy convocation; ye shall do no manner of servile work therein: but ye shall offer a sacrifice made by fire for a burnt offering unto the LORD; two young bullocks, and one ram, and seven lambs of the first year: they shall be unto you without blemish