The Pentecost (Feast of Weeks) was celebrated together with the firstfruits of the wheat harvest (Exodus 23:16; Exodus 34:22; Numbers 28:26) in order to commemorate and remember that the Lord had brought Israel into the land, and that he is the one who provided them with a harvest (food) to eat (Leviticus 23:10). The coming of the Holy Spirit at Pentecost connects with this idea. He is the firstfruit given to the church (Romans 8:23; Ephesians 1:13–14); the full harvest (resurrection bodies and life in a new creation) will come when Christ returns.1 This is confirmed by the Greek word used in this first sentence. Translated by the NIV as came
it has the meaning fulfilled
suggesting that the outpouring of the Holy Spirit is the fulfillment of the old covenant feast.2
1 When the day of Pentecost arrived, they were all together in one place.