Deuteronomy 24:21
When thou gatherest the grapes of thy vineyard, thou shalt not glean it afterward: it shall be for the stranger, for the fatherless, and for the widow. When thou gatherest the grapes of thy vineyard, thou shalt not glean it afterward: it shall be for the stranger, for the fatherless, and for the widow.
When grapes are gathered the vineyard owner must not take the harvest completely and must not go back to glean the vines afterward, whether after a first picking or a second time, but must leave what remains unpicked and ungleaned for the stranger, the fatherless, and the widow to gather. The grapes left after the owner's harvest are theirs, not as charity alone but as what belongs to them by right. This leaving of grapes was part of a larger provision by which the poor and needy could obtain food from fields, orchards, and vineyards.
God's law in this way makes practical provision for people in need and protects them from deprivation and oppression. Withholding what is due to the poor is condemned as injustice. The command teaches practical mercy, fair and generous treatment, care, and love, rather than taking every possible benefit for self or seeking everything for personal gain.
Following the command was part of doing God's will and receiving His blessing. This harvest generosity was Israel's response to God's mercy, remembered especially in light of former bondage in Egypt, with the joy of harvest joined to praise and thanksgiving to God. Keeping this law brings God's blessing on all the work of the hands.
The stranger was to be treated kindly and loved rather than looked down on because he was not of Israel. Even so Israel was to stand distinct and holy and separate from the nations that did not know God. The stranger was to be welcomed at feasts of thanksgiving to share in God's blessings when His mercies are recounted.
The command rests on God's benevolence in giving the blessings of salvation, temporal as well as spiritual, for all mankind, with ample provision for the wants of all to be supplied through those entrusted with His goods. Christ died as truly to save the stranger as to save Israel. The principle extends beyond grapes to sharing both material and spiritual blessings with the world. Those who choose the society of those who know and acknowledge God are to be received so they may learn the law of Jehovah and glorify Him by obedience.
For Christians the same law requires strict integrity in all the details of life, serving God rather than selfish gain and doing business as under God's eye. It forbids enlarging possessions by taking advantage of a neighbor's need. It requires relieving the necessities of a less fortunate brother, paying laborers their hard-earned money, accepting only a fair price, and frankly telling buyers of defects even at cost to self.
Together with the harvest instructions in the surrounding verses, this instruction gave specific guidance and a spiritual advantage and opportunity to show love and mercy. But the Jewish nation failed to follow it and neglected both the temporal and religious needs of suffering people.