Albert Barnes Commentary Numbers 28:26-31

"Also in the day of the first-fruits, when ye offer a new meal-offering unto Jehovah in your [feast of] weeks, ye shall have a holy convocation; ye shall do no servile work; but ye shall offer a burnt-offering for a sweet savor unto Jehovah: two young bullocks, one ram, seven he-lambs a year old; and their meal-offering, fine flour mingled with oil, three tenth parts for each bullock, two tenth parts for the one ram, a tenth part for every lamb of the seven lambs; one he-goat, to make atonement for you. Besides the continual burnt-offering, and the meal-offering thereof, ye shall offer them (they shall be unto you without blemish), and their drink-offerings." — Numbers 28:26-31 (ASV)

The festival offering at the season of first-fruits was to be offered on one day only; and was the same as that of the new moon and Passover. It nearly, though not entirely, corresponds with the sacrificial offering prescribed in Leviticus 23:18 and following.