Of the hundreds of laws in the Old Testament, one of the most striking deals with the ancient Israelite attitude toward those who have rights to the product of the harvest. It was a terribly important issue, since ancient Isreal was an agricultural society, and wealth was primarily measured by land ownership and productivity, as well as farm animals. The Book of Leviticus expressed the idea as follows: "When you reap the harvest of your land, you shall not wholly reap the corners of your field, nor gather the gleaning of your harvest...you shall leave them for the poor and the stranger: I am the Lord your God" (Lev 19:9-10).
Though ancient Isreal tried to keep very clear distinctions between who was "inside" and who was "outside" of its community, it recognized that there were vulnerable classes of people in the land. Rather than exploit or ignore these vulnerable groups, the law recognized them and gave them a specific claim on the harvest. The two groups mentioned here were the "poor" and the "stranger." Of course we don't know fully how one qualified for membership in these groups, but what is striking about the latter category (the ger in the Hebrew) is that they were people who couldn't acquire land in Israel. They were either recent arrivals or non-Israelites, and thus were at the mercy of those who were settled in the land.
The law, and the Lord, took special cognizance of these people by requiring the landowner to leave some of the land unharvested, and not to be too quick to pick up every last gleaning. These were to be harvested by the poor and the alien/stranger. There is no better way to foster loyalty among workers, as well as a sense of gratitude and hospitality among those with much, than to share in the fruit of the harvest. Isreal didn't think this was just a good idea: the final words of the quoted passage says it all: "I am the Lord your God." God, it seems also has a heart for the poor and the stranger.