Numbers 18:12
All the best of the oil, and all the best of the wine, and of the wheat, the firstfruits of them which they shall offer unto the LORD, them have I given thee. All the best of the oil, and all the best of the wine, and of the wheat, the firstfruits of them which they shall offer unto the LORD, them have I given thee.
Under the old ministration the firstfruits of oil and wine and wheat offered to the Lord were given to the priests for their use as God's servants. What was required was not any portion indiscriminately, but the best of the produce. By this appointment Israel was taught to put God first and to acknowledge Him as the owner of their fields and their harvests. Set against such provision, to withhold even the gleanings from those who serve exposes the lack and the need of a spirit of sacrifice.