Deuteronomy 24:19-22

19“When you reap your harvest in your field and have forgotten a sheaf [of grain] in the field, you shall not go back to get it; it shall be for the stranger, for the orphan, and for the widow, so that the Lord your God may bless you in all the work of your hands.

20When you beat [the olives off of] your olive tree, do not search through the branches again; [whatever is left] 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.

22You shall [thoughtfully] remember [the fact] that you were a slave in the land of Egypt; therefore I am commanding you to do this thing.