The last chapter concluded the historical account as Moses recounted all the events from when Israel departed Mount Sinai to their arrival in the plains of Moab opposite the promised land. In the Hittite Suzerainty treaty, this corresponds with the prologue. The next section of the treaty form is the stipulations, a list of requirements or laws that the vassal must obey, and this corresponds with the ten commandments in the next chapter.
This chapter falls between the two, and seems to have elements of each. From the prologue, this chapter includes references to many events from Israel's past. Moses specifically refers to the sin of Baal-Peor (v. 3-4), the giving of the law of Mount Sinai (v. 10-14), and Moses's sin at Meribah (v. 21-22). From the stipulations, Moses instructs the people to "keep the commandments of the LORD your God which I command you" (v. 2), "do thus [the statues and judgments of the LORD] in the land where you are entering to possess it" (v. 5), "keep his statutes and his commandments" (v. 40).
The core message of this chapter (and really, a lot of Deuteronomy at large) is that because of the LORD's actions towards the Israelites, the Israelites should respond by obeying his commands and following him alone, and this shows the connection between the prologue (what the LORD did) and the stipulations (how the Israelites should respond). On an encouraging note, Moses reminds Israel of the LORD's appearance from Ex 19 (in this chapter, v. 10-14), when the covenant was first declared.
In v. 3, the Israelites are given a much more negative reminder, that as in the case of Baal-Peor, the LORD will destroy anyone who follow other gods. This warning is reiterated and broadly extended in v. 25-28. The warning in v. 25-28 is also reminiscent of the warning in Lev 26. In both cases, the LORD promises destruction for Israel if they do not keep his commands and seek after other gods. What we can see from the "affair of Peor" is that the LORD kept his promise, destroying "the men who followed Baal-Peor" (v. 3). In the earlier incident of the golden calf, the LORD relented from destroying the whole nation, but even then 3,000 men died (Ex 32:28). Moses also promises that when the people are "[scattered] among the peoples, and you will be left few in number among the nations" that they would turn fully to idolatry just as they worshiped the gods of Egypt while in slavery. This is a truly dire fate as the people suffer and depart completely from the LORD. But what's fascinating is that Moses predicts a revival: "from there you will seek the LORD your God, and you will find him if you search for him with all your heart and all your soul". This is really groundbreaking because everything we have seen so far is a prediction of destruction and misery if the Israelites turn away from the LORD.
Lev 26 also included a conditional revival, that if the Israelites "confess their iniquities... then I will remember my covenant with Jacob..." (Lev 26:40). In that chapter, all of the blessings and curses are conditional, and the renewal of Lev 26:40-45 is also conditional upon the people returning to the LORD. Deut 4:25-31, on the other hand, is predictive, stating that the people will act corruptly, be driven from the land, suffer and worship other gods in other lands, and from there they will repent and seek the LORD. In that place, the LORD will be found by them, because "the LORD your God is a compassionate God; he will not fail you nor destroy you nor forget the covenant..." (v 31).
This is all really stunning for two reasons. One, the LORD allows the Israelites to return even after they break the covenant, so long as they return with wholeheartedness. Two, the LORD will be found "if you search for him with all your heart and all your soul". This isn't exactly a general statement, but it's pretty close. I mean, if you can find the LORD from a place of deepest darkness, you can certainly find him from better places as well. And I think that's why this passage is so amazing, because even here in the Pentateuch, one of the earliest books in the OT, the LORD is willing to forgive the darkest of sins. This is what I think a lot of people miss in the OT; they miss the profound forgiveness and mercy that the LORD shows towards Israel in spite of all the wrongs that Israel has done in the past and will do in the future.
Verse 26 also calls heaven and earth as witnesses, another part of the Hittite treaty. This expression is used three times in the OT, and all three of those references are in Deuteronomy (here, 3:26, also in Deut 30:19 and 31:28). Normally the witnesses to a Hittite treaty would be the gods of the suzerain and the vassal nations, but since this is a treaty between Israel and their God, the author improvises and calls the natural and spiritual realms of existence as witnesses.
One interesting connection in this chapter is that Moses says the Israelites saw no form when the LORD descended on Mount Sinai, and that's why they are to not make an idol in the form of any creature of the earth. The LORD did not come with a physical form because he transcends material shapes and boundaries. To craft an idol, even if you think it's the LORD (e.g. Ex 32:5) is to denigrate and diminish the true power of the LORD by making him into something lesser, weaker than he really is.
This chapter also calls the LORD a "consuming fire, a jealous God". The term "consuming fire" was used previously in Ex 24:17 to describe the appearance of the mountain top when the LORD's glory dwelt upon it and Moses entered to confirm the covenant. I think this is another reason why there is a lampstand perpetually burning in the tabernacle, because an eternally burning flame resembles the LORD. That fire is compared to jealousy, and the LORD was also called a jealous God in Ex 20:5, part of the second commandment against making idols, and later in Ex 34:14, a command to destroy all the idols of the Canaanites when the Israelites enter the promised land, lest they be ensnared by sin. The jealousy is a demand for wholeheartedness, that the Israelites obey and follow the LORD alone and seek after no other gods.
Another one of my favorite verses from this chapter is v. 39: "Know therefore today, and take it to your heart, that the LORD, he is God in heaven above and on the earth below; there is no other." But really the entire section from v. 32-40 is fantastic. I don't think it's needs an explanation or anything, but I just love the language and the progression. It involves the repeated use of heavens and earth. To paraphrase,
Man was created on earth, now inquire in the heavens from one end to the other: has anything like this been done? Out of the heavens he let you hear his voice, and on earth he let you see his great fire, and you heard his words from the midst of the fire. Know therefore that there is no other god in the heavens above or the earth below.These are the same heavens and the earth that are called as a witness to the covenant, so the LORD is essentially calling his entire dominion of creation as a witness to his treaty with the people.
Also, this passage has really fantastic poetic structure. In v. 34, Moses lists all the ways that the LORD brought Israel out of Egypt, first with a triplet of related terms, "trials, signs and wonders" (this triplet is a common literary device), then with a chiasm (ABBA structure), "war, a mighty hand, an outstretched arm, and by great terrors". Verse 35 states that "the LORD, he is God, there is no other besides him", which is repeated in a stronger fashion in v. 39, "the LORD, he is God in heaven above and on the earth below; there is no other." Verse 36 contains a CACBAB structure with the word pairs "voice/words", "heaven/earth" and "fire": "out of the heavens he let you hear his voice to discipline you; and on earth he let you see his great fire, and you heard his words from the midst of the fire." If I remove all the extra text, you can read it like "heavens, voice, earth, fire, words, fire." Intermixing the voice and fire of the LORD with the repetition of the terms "heavens" and "earth", the overall effect is to emphasize the LORD's dominion over heaven and earth, expressed through the signs, wonders and his might hand, bringing Israel out of Egypt and then speaking to them from the fire.
The fire is a dual expression of the LORD's zeal for Israel and his power over the nations of the earth, which is most clearly expressed when the LORD descends upon Mount Sinai in a raging whirlwind of fire, rendering the whole mountain like a smoking furnace (Ex 19). Of course, that was when Moses had grown in his appreciation of the LORD and was willing to ascend the mountain (an almost unthinkable act to his compatriots). When Moses first met the LORD, it was in a much humbler form, a burning bush (Ex 3). In a few short years, the LORD could now appear to Moses as a burning mountain, which really tells us more about the growth of Moses than any change in the LORD.
The structure in v. 36 binds the words "fire" and "voice" together, which is apt when we recall that it was from the burning bush that the LORD first commissioned Moses to speak to Pharaoh and bring about the freedom of his people. Interestingly, the burning bush is what commissions Moses to free Israel from Egypt, while the burning mountain is what largely concludes the Exodus story and kicks off the next phase (the desert wandering). These two events provide a frame around the Exodus story and tie it all together as it was the LORD's divine intervention that brought the nation out of slavery. Now Moses is encouraging the Israelites to remember how they were freed from Egypt, and on that basis to obey the voice that they heard from the fire.
Moses concludes by establishing the three cities of refuge in Transjordan and there is a concluding paragraph to show us that this ends the first section of Deuteronomy. The next section begins in chapter 5 with a second oration of the ten commandments.