19. When you cut down your harvest in your field, and have forgotten a sheaf in the field, you shall not go again to fetch it; it shall be for the stranger, for the orphan, and for the widow; that the Lord your God may bless you in all the work of your hands.
20. When you beat your olive tree, you shall not go over the boughs again; it shall be for the stranger, for the orphan, and for the widow.
21. When you gather the grapes of your vineyard, you shall not glean it afterward; it shall be for the stranger, for the orphan, and for the widow.
22. And you shall remember that you were a slave in the land of Egypt; therefore I command you to do this thing.
These gifts to the poor are one key example of helping those in need. While beneficial to the poor, one can certainly argue that what is left behind is not enough to actually sustain the needy. A number of commentaries suggest that the primary purpose of these commandments is to build the moral personality of the owner of the field who must understand there are limits even to his/her ownership of the property. The poor also have a claim to it, albeit limited to certain categories. God is after all, the true owner of the field.
The forgotten sheaf which must be left for the poor is an odd example of a commandment to fulfill. There can be no intent here by definition, the sheaf was forgotten. I am forbidden to return to harvest it. It must remain forgotten. In a religion in which memory is so foundational, and it is precisely because we are commanded to remember we were slaves in Egypt, that when it comes to sheaves in the field, I must truly learn how to forget.
As we struggle in Elul to honestly look at ourselves and begin to reconcile with those we have hurt, we must first remember where we erred with others and with God. With repentance and forgiveness must then come a form of forgetting as we begin the new year.
For a full discussion, please see Nehama Leibowitz Studies in Deuteronomy pp 243-249.