Which is greater?

"Fools and blind! For which is greater, the gold or the temple that sanctifies the gold? [...] Fools and blind! For which is greater, the gift or the altar that sanctifies the gift?" Matthew 23.17-19

Tithes and offerings carry a revelation in itself: what is in the offering giver's heart.
Firstfruits show faithfulness and offerings reveal love.
While there was no sin in the world, tithes and offerings were not necessary, since the communion between the creature and the Creator was perfect. With sin came the moral and spiritual corruption. Therefore, God established the tithe and offerings to prove the heart of those who approached Him.

The Promise

"...that the blessing of Abraham might come upon the Gentiles in Christ Jesus, that we might receive the promise of the Spirit through faith." Galatians 3.14

Abraham was the firstfruits of God to bless his descendants. He typified Jesus, the Firstborn of God, to bless the Jews who believe.
Jesus came to extend the Abrahamic blessing to the Gentiles who believe in Him. This blessing is not limited to material possessions, but above all, to receive His Spirit.

Firstfruits

"Of His own will He brought us forth by the word of truth, that we might be a kind of firstfruits of His creatures." James 1.8

Through the Lord Jesus, the Word, each one of those who are born of the Holy Spirit is God's first fruits, His firstborn, His tithe, His property, holiness to Him, in short, they are children of God.
Do you think this a small thing?
Then, wait until you get to the glorious New Jerusalem to see what the Almighty has in store for each of His own.

Holiness and firstfruits

"Israel was holiness to the LORD, the firstfruits of His increase..." Jeremiah 2.3

Israel had double honour before God: it was the firstfruits and holy. Those who are born of the Spirit of God have the same characteristics: they are the first fruits and the sole property of the Almighty. Therefore, the Holy Spirit guarantees that everyone who is born of God overcomes the world (1 John 5.4).

Israel was...

"Israel was holiness to the LORD, the firstfruits of His increase. All that devour him will offend; disaster will come upon them, says the LORD." Jeremiah 2.3

To be holy to the LORD means to be His property. To be the first fruits of the harvest of the Lord means to be His tithe. That is how Israel was before the Most High. What is your situation before the LORD: are you or were you consecrated unto the LORD? Are you or were you the tithe of the LORD?

First Fruits Day

"O God, You are my God; Early will I seek You; My soul thirsts for You; My flesh longs for You in a dry and thirsty land where there is no water."

Psalms 63:1

As the first day of the week, today is the day of the first fruits to God. It's the day that the family dedicates to the Lord, to offer a living offering before Him in order to drink of the Living Waters and have their thirst met and life protected for the rest of their week.