10 And thou shalt not glean thy vineyard, neither shalt thou gather every grape of thy vineyard; thou shalt leave them for the poor and stranger: I am the LORD your God.
During the harvest, [the law] forbids owners to gather up the bits which fall from the sheaves and similarly advises that in harvesting something should be left behind unreaped. By this it gives excellent teaching to owners in the practice of generous sharing by leaving some of their property for those in need and providing the poor with a chance for food.
Do you see how the law proclaims simultaneously the justice and goodness of God, who provides food unstintingly for all? Again, in the grape harvest the harvesters are forbidden to go back and cut anything that has been left over or to collect fallen grapes. The same rules are applied to olive gatherers. In fact the principle of tithing crops and flocks was an education in honoring the divine. We are not to be totally absorbed by profit but to share humanely with the neighbor as well.
[AD 215] Clement of Alexandria on Leviticus 19:9-10