Albert Barnes Commentary Numbers 28:16-25

"And in the first month, on the fourteenth day of the month, is Jehovah`s passover. And on the fifteenth day of this month shall be a feast: seven days shall unleavened bread be eaten. In the first day shall be a holy convocation: ye shall do no servile work; but ye shall offer an offering made by fire, a burnt-offering unto Jehovah: two young bullocks, and one ram, and seven he-lambs a year old; they shall be unto you without blemish; and their meal-offering, fine flour mingled with oil: three tenth parts shall ye offer for a bullock, and two tenth parts for the ram; a tenth part shalt thou offer for every lamb of the seven lambs; and one he-goat for a sin-offering, to make atonement for you. Ye shall offer these besides the burnt-offering of the morning, which is for a continual burnt-offering. After this manner ye shall offer daily, for seven days, the food of the offering made by fire, of a sweet savor unto Jehovah: it shall be offered besides the continual burnt-offering, and the drink-offering thereof. And on the seventh day ye shall have a holy convocation: ye shall do no servile work." — Numbers 28:16-25 (ASV)

The Passover offering was the same as that of the New Moon, and was repeated on each of the seven days of the festival, thus marking the importance and the solemnity of the occasion. The details of the offering had not been previously prescribed.