(For the fruit of the Spirit is in all goodness and righteousness and truth;) – Ephesians 5:9

It is called “first-fruits,” because the first-fruits were always the pledge of the harvest. As soon as the Israelite had plucked the first handful of ripe ears, they were to him so many proofs that the harvest was already come. He looked forward with glad anticipation to the time when the wain should creak beneath the sheaves, and when the harvest home should be shouted at the door of the barn. So, brethren, when God gives us “Faith, hope, charity-these three,” when He gives us “whatsoever things are pure, lovely, and of good report,” as the work of the Holy Spirit, these are to us the prognostics of the coming glory. If you have the Spirit of God in your soul, you may rejoice over it as the pledge and token of the fulness of bliss and perfection “which God hath prepared for them that love Him.”

It is called “first-fruits,” again, because these were always holy to the Lord. The first ears of corn were offered to the Most High, and surely our new nature, with all its powers, must be regarded by us as a consecrated thing. The new life which God has given to us is not ours that we should ascribe its excellence to our own merit: the new nature is Christ’s peculiarly; as it is Christ’s image and Christ’s creation, so it is for Christ’s glory alone. That secret we must keep separate from all earthly things; that treasure which He has committed to us we must watch both night and day against those profane intruders who would defile the consecrated ground. We would stand upon our watch-tower and cry aloud to the Strong for strength, that the adversary may be repelled, that the sacred castle of our heart may be for the habitation of Jesus, and Jesus alone. We have a sacred secret which belongs to Jesus, as the first-fruits belong to Jehovah. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0788.cfm