Deuteronomy 26:2
That thou shalt take of the first of all the fruit of the earth, which thou shalt bring of thy land that the LORD thy God giveth thee, and shalt put it in a basket, and shalt go unto the place which the LORD thy God shall choose to place his name there.
Israel was directed to take the first of all the fruit of the earth from the land the Lord their God gave them and bring it to the place He chose to place His name for worship. The first produce was to be put in a basket and carried to that place. The offering recognized that the land and its blessings came from God, and the firstfruits were thereby consecrated to Him. It was an act of gratitude for His goodness and gifts.
It also gratefully acknowledged Israel's deliverance from Egypt and settlement in the land. It was to be presented in worship with rejoicing and shared with the Levite and the stranger, the fatherless, and the widow. It is acceptable only when presented with a humble, reverent, grateful heart, and is unacceptable when given from self-sufficiency or as though God were indebted to the giver.
It was a continuing requirement and a practical direction within God's law, expressing His continuing claim on those He has blessed. It was meant to keep them mindful of their duty to obey and to publicly recognize His blessings, with blessings promised for obedience.