In this chapter, the LORD restates some laws of the covenant and adds a few new ones, too.
Some of the commands in this chapter are a repetition of things we have been told before, so I will not discuss them in depth. Verses 2-4, 11-12, 30, 32 for instance are largely taken from the ten commandments of Ex 20. Then verse 5-8 are a repetition of Lev 7:15-18. Verses 26 and 31 also convey laws similar to previously.
Mixed with the old are some new commands, too. I will discuss these in the order they are listed.
First is a command that the "very corners" of fields shall be left unharvested and the "gleanings" should be left as well, i.e. what remains after a first pass of the harvesters. The idea (as we are told in v. 10) is that there should be bits and pieces of the harvest left in the field so that people traveling through can eat stuff from the corners and be provided for in that fashion. In this law we can see the agricultural future of Israel, and this law actually becomes a significant issue in ancient Israeli society. In the story of Ruth for instance (which we will see later), the eponymous Ruth spends some time following the harvesters of a man named Boaz, legally gathering the gleanings that were left behind. I.e. whatever was missed by the harvesters on their first pass was "fair game" for Ruth to gather for herself, because she did not have a field of her own to harvest.
Naturally, not all Israelites obeyed this law, and that is part of the charge of injustice that is later levied against them by the prophets.
Second is the charge to not oppress hired workers, which is similar to the earlier command regarding cloaks taken as a pledge (Exodus 22:26). In verse 14, the curse would have been audible, so a deaf man is incapable of hearing it and protecting himself. The blind man cannot see the stumbling block, and is therefore helpless against people who attack him in this way. In general, do not take advantage of the weaknesses of others, where they cannot protect themselves.
Verses 17-18 contain possibly one of the greatest commands in the OT, that "you shall not hate your fellow countryman in your heart... but you shall love your neighbor as yourself." This is really fantastic, and after writing for so long about homosexuality in the last chapter, I feel I would do a great injustice to not spend some time on this command as stated here. However, since the interpretation is so straightforward (if significant) that I'm not sure how much commentary I can properly add. Also, it's much less contentious, so I feel there is less general confusion and misinformation relating to "love your neighbor" when compared to the prohibitions of homosexuality, so while I think it's truer to the core of Christianity (and Judaism), it's also less debated.
Certainly this verse runs contrary to the popular perception of the OT as the "wrathful, angry God book", as do many of the justice laws in this chapter and elsewhere. This verse is significant enough to be mentioned by Jesus as the second greatest commandment (Matthew 22:39), just behind loving God. Just as Jesus expressed, I think this verse forms part of the moral backbone to the Mosaic Law, because it summarizes all of the justice laws. What is the purpose of not stealing, not murdering, acting justly, leaving gleanings for the poor, judging and speaking truthfully, if it is not to love your neighbors? All of these principles are united by the concept of justice, and yet leaving gleanings goes beyond fairness: it is a command to materially help others in need. More than fairness, it is a self-sacrificial concern for others that the LORD demands of his people.
This is a more ambiguous command than the earlier systematic laws regarding sacrifices or the punishment of various sins, and the ambiguity itself is an unusual departure from the mainstream thrust of the Mosaic Code. What we will find is that in many cases, the ambiguity renders this law less effective because it is commanding not an action, but a mindset, so how can we obtain evidence of guilt? Loving your neighbor is the heart of these laws, and yet it is nearly impossible to prosecute, so in many cases we find that people will obey the details of the law (with sacrifices, not stealing and murdering and so forth) while ignoring the heart of it, which is the attitude of love and concern for others. This is one of the main criticisms we find in the NT and it remains a substantial issue in modern Christianity. A full discussion of this subject is outside of my scope however, and I will postpone it until the NT section.
There is a simple dichotomy in Christianity, which is that as a man, we should forgive and love others, even those who do wrong. As verse 18 says, we shall not take vengeance or bear any grudge. God is the avenger of wrongs, as he holds an accounting of blood (Gen 9:5-7), and anyone who sheds blood bears the judgment of God. In the OT, that vengeance is generally carried out by men, however, which is a source of confusion for many. For instance, Genesis 15:16 speaks of a coming judgment of the Amorites through the return of the Israelites to the promised land, i.e. wiping them out. This is a judgment upon the "iniquity of the Amorites". In the last chapter, Leviticus 18, we are told that it is by defiling the land that the nations would be cast out. This is a divine judgment of sin, yet the punishment is carried out by an invading nation destroying them. So how can I say that God is the judge of sin when men are expected to carry out that judgment?
This might seem like a subtle distinction, but it is important: the justice carried out in the OT must be at the direction of the LORD, because the LORD is the "judge of all the earth" (Gen 18:25) and it is not proper for mankind to usurp that role of judge. We can make judgments, but only under the authority of the LORD, and we can maintain laws and punish lawbreakers, but only if those laws come from the lawgiver, the LORD. This is a question of authority, whether mankind has authority to create their own justice, and the answer is significant: we do not. If human laws mirror the laws given by God, then Christians can simply follow those laws. But when there is a difference between the two, Christians do not have authority to follow the laws of man and violate the laws of God, so a conflict with men is inevitable. See, for instance, Acts 4:19-20.
Moving on, verse 19 seems peculiar, and I like to think of it as a symbolic extension of the principle of separation, that just as the Israelites are supposed to stay distinct from the nations around them, they are also expected to maintain a "separation" between fabrics, species of animals and seeds in their fields.
There are some more slavery laws, and then in v. 23 is a command that fruit not be eaten for three years, the fourth year is a giant offering to the LORD (probably given to the priests), and after that the crops may be eaten. This command is probably similar to the seventh year Sabbath command we were given before, with an intent to help the crop trees multiply and enrich the soil. Farming implies a certain level of burden on the ground, and this three-year Sabbath will help prepare the land for that burden.
Verse 27-28 is a command against practices associated with the pagan religions of the area, and to this day most Orthodox Jews will not shave their beards for this reason. The biblical command is to avoid religious practices associated with hedonism, not because shaving one's beard is inherently sinful. In that sense, this command is similar to the earlier command about only offering sacrifices at the tabernacle, which was intended to cut off any association with pagan worship or sacrifice.
In case anyone doubted that the command in v. 18 was only for fellow Israelites, the LORD resolves any doubts with v. 33-34, similarly commanding that the people must "not do [strangers] wrong" and "you shall love him as yourself" and is given a direct equivalence that the foreigner shall be "like the native among you", discounting any possible racism in the law, though racism was still a reality in practice. This verse does not prohibit maltreatment of other nations, however. It only prohibits doing wrong to people from other nations living in the land of Israel, where the Israelis have all of the power. Essentially this is all about protecting people who are too weak to protect themselves, and foreigners as a group would not have the same social and cultural support when living amongst another nation. The Israelites are to respect their own humble beginnings, first as a wandering family in the promised land and then later as a growing yet oppressed nation within the land of Egypt.
Lastly, v. 35-36 demands justice in measurements, because one effect way to scam people in this time period is to have "two scales", a light scale and a heavy scale, so that you can weigh goods you sell them with a "light scale" (overestimating its weight) and weigh their gold or silver with the "heavy scale" (underestimating their payment). In this way you can charge people a higher price than you make apparent. God prohibits any such deception.