And ye shall offer with the bread seven lambs without blemish of the first year, and one young bullock, and two rams: they shall be for a burnt offering unto the LORD, with their meat offering, and their drink offerings, even an offering made by fire, of sweet savor unto the LORD.

Wesley's Notes

23:18 One bullock and two rams - In Num 28:11,19, it is two young bullocks and one ram. Either therefore it was left to their liberty to chuse which they would offer, or one of the bullocks there, and one of the rams here, were the peculiar sacrifices of the feast day, and the other were attendants upon the two loaves, which were the proper offering at this time. And the one may be mentioned there, and the other here, to teach us, that the addition of a new sacrifice did not destroy the former, but both were to be offered, as the extraordinary sacrifices of every feast did not hinder the oblation of the daily sacrifice.

Matthew Henry's Concise Commentary

23:15-22 The feast of Weeks was held in remembrance of the giving of the law, fifty days after the departure from Egypt; and looked forward to the outpouring of the Holy Ghost, fifty days after Christ our Passover was sacrificed for us. On that day the apostles presented the first-fruits of the Christian church to God. To the institution of the feast of Pentecost, is added a repetition of that law, by which they were required to leave the gleanings of their fields. Those who are truly sensible of the mercy they received from God, will show mercy to the poor without grudging.

Matthew Henry's Whole Bible Commentary

Verses 15-22

Here is the institution of the feast of pentecost, or weeks, as it is called (Deu. 16:9), because it was observed fifty days, or seven weeks, after the passover. It is also called the feast of harvest, Ex. 23:16. For as the presenting of the sheaf of first-fruits was an introduction to the harvest, and gave them liberty to put in the sickle, so they solemnized the finishing of their corn-harvest at this feast. 1. Then they offered a handful of ears of barley, now they offered two loaves of wheaten bread, v. 17. This was leavened. At the passover they ate unleavened bread, because it was in remembrance of the bread they ate when they came out of Egypt, which was unleavened; but now at pentecost it was leavened, because it was an acknowledgment of God's goodness to them in their ordinary food, which was leavened. 2. With that sheaf of first-fruits they offered only one lamb for a burnt-offering, but with these loaves of first-fruits they offered seven lambs, two rams, and one bullock, all for a burnt-offering, so giving glory to God, as the Lord of their land and the Lord of their harvest, by whose favour they lived and to whose praise they ought to live. They offered likewise a kid for a sin-offering, so taking shame to themselves as unworthy of the bread they ate, and imploring pardon for their sins, by which they had forfeited their harvest-mercies, and which they had been guilty of in the receiving of them. And lastly, two lambs for a sacrifice of peace-offerings, to beg a blessing upon the corn they had gathered in, which would be neither sure nor sweet to them without that blessing, Hag. 1:9. These were the only peace-offerings that were offered on the behalf of the whole congregation, and they were reckoned most holy offerings, whereas other peace-offerings were but holy. All these offerings are here appointed, v. 18-20. 3. That one day was to be kept with a holy convocation, v. 21. It was one of the days on which all Israel was to meet God and one another, at the place which the Lord should choose. Some suggest that whereas seven days were to make up the feast of unleavened bread there was only one day appointed for the feast of pentecost, because this was a busy time of the year with them, and God allowed them speedily to return to their work in the country. This annual feast was instituted in remembrance of the giving of the law upon mount Sinai, the fiftieth day after they came out of Egypt. That was the feast which they were told in Egypt must be observed to God in the wilderness, as a memorial of which ever after they kept this feast. But the period and perfection of this feast was the pouring out of the Spirit upon the apostles on the day of this feast (Acts 2:1), in which the law of faith was given, fifty days after Christ our passover was sacrificed for us. And on that day (as bishop Patrick well expresses it) the apostles, having themselves received the first-fruits of the Spirit, begat three thousand souls, through the word of truth, and presented them, as the first-fruits of the Christian church, to God and the Lamb.

To the institution of the feast of pentecost is annexed a repetition of that law which we had before (ch. 19:9), by which they were required to leave the gleanings of their fields, and the corn that grew on the ends of the butts, for the poor, v. 22. Probably it comes in here as a thing which the priests must take occasion to remind the people of, when they brought their first-fruits, intimating to them that to obey even in this small matter was better than sacrifice, and that, unless they were obedient, their offerings should not be accepted. It also taught them that the joy of harvest should express itself in charity to the poor, who must have their due out of what we have, as well as God his. Those that are truly sensible of the mercy they receive from God will without grudging show mercy to the poor.