4:18–20 Moses returns from the mountain to his father-in-law, Jethro, seeking permission to return to Egypt (v. 18). For Moses to take his wife and children (Jethro’s daughter and grandchildren) and leave without asking would seriously breach family protocol (cf. Gen. 31:17–28).

Moses does not tell Jethro the full story at this point (though we are not told why). Rather, he mentions his natural desire to see whether his “brothers” are still living—likely a reference either to his relatives (the same word is translated “kinsmen” in Gen. 13:8) or to fellow Israelites in general.117 Jethro agrees to the request, and after an unspecified amount of time the Lord commands Moses to return to Egypt, assuring him that those seeking his life have died (Ex. 4:19; cf. 2:15). So Moses puts his wife (Zipporah) and his sons (Gershom and Eliezer) onto a donkey and begins the journey (4:20a). The narrator highlights that Moses takes his “staff” with him (v. 20b), signaling again that it will be central to the coming drama (cf. comment on 4:13–17). Indeed, it is called the “staff of God” (cf. 17:9), presumably because God will work miracles by it. In any case to have a “staff of God” is to have a divine weapon and to be equipped to do mighty things.

4:21–23 Either before or during the journey the Lord again gives Moses a preview of what will take place in Egypt (vv. 21–23; cf. 3:16–22). He focuses especially on his sovereignty over Pharaoh and on Israel’s status as his firstborn son.

In terms of sovereignty the Lord commands Moses to perform the signs before Pharaoh and then states, “But I”—the Hebrew emphasizes the pronoun—“will harden his heart, so that he will not let the people go” (4:21). References to Pharaoh’s heart’s being “hard” occur throughout these chapters (7:3, 13, 14, 22; 8:15, 19, 32; 9:7, 12, 34, 35; 10:1, 20, 27; 11:10; 14:4, 8; cf. 14:17). Although it is hard to see in English translations, three different Hebrew roots are used (hazaq, qashah, kaved). These appear to be used interchangeably, however, so that a consistent English translation such as “to harden/be hard” or “to make stubborn/be stubborn” is justifiable.118 It may also be noted how the words are used with three different subjects: (1) the Lord, who hardens Pharaoh’s heart (4:21; 7:3; etc.); (2) Pharaoh, who hardens his own heart (8:15, 32; 9:34); and (3) Pharaoh’s heart, which is said to be hard/hardened (7:13, 14; 8:19; etc.).

In Exodus to have a “hard heart” is not to lack compassion (which is what English speakers often mean by such language). Rather, the phrase refers to a heart that is rebelliously stubborn in its refusal to change. Once the signs of chapters 7–14 start a discernible pattern is evident. Before the sign Pharaoh stubbornly refuses to obey the Lord’s command. This is named first in 5:1–2 and stays consistent throughout the chapters. After the sign Pharaoh continues his stubborn refusal to obey the Lord’s command (7:14, 22; 8:15, 19, 32; 9:7, 12, 34, 35; 10:20, 27–28; 14:4, 8). In between these two responses his heart is said to be hard or to be hardened by himself or the Lord (7:13, 14, 22; 8:15, 19, 32; 9:7, 12, 34, 35; 10:1, 20, 27; 11:10; 14:4, 8; cf. 14:17). In short the effect of his heart’s being hard or hardened is that Pharaoh continues in his sinful path, impervious to change and even strengthened in his rebellious stubbornness.

To return to our passage, when the Lord says, “I will harden his heart” (4:21), he is not speaking of taking a good heart and making it bad. Pharaoh has long ago decided to treat the Israelites as slaves and oppress them brutally.119 Rather, the Lord is saying he will take a heart hardened in rebellion and make it harder still, strengthening it in its deepest convictions,120 “seconding, as it were,” Pharaoh’s own earlier decision to harden it.121 In a sobering punishment that fits the crime the Lord sometimes judges us by giving us over to our heart’s evil desires and then bringing his justice to bear against us for the evil we commit (cf. esp. 9:34 with 10:1; cf. also Ps. 81:11–12 and esp. Rom. 1:28–32). This is a severe warning about the danger of sin, which coats our hearts like quick-drying cement, making repentance increasingly difficult and judgment increasingly certain.

In sum the sense of “hardening” with each of the different subjects is as follows: (1) the Lord “hardens” Pharaoh’s stubborn heart, that is, makes it harder still (4:21; 7:3; 9:12; 10:20, 27; 11:10; 14:4, 8, 17 [Egypt’s heart]); (2) Pharaoh “hardens” his stubborn heart, that is, makes it harder still (8:11, 28; 9:34 [joined by his servants]); and (3) Pharaoh’s stubborn “heart is hard/hardened,” that is, continues in its stubborn rebellion and becomes harder still (7:13, 14, 22; 8:15; 9:7, 35).

Along with his sovereignty over Pharaoh the Lord also highlights Israel’s status as his “firstborn son” (4:22–23). This status has at least two implications. First, it assumes the Lord’s special love for his people.122 In ancient Israel firstborn sons held a special place in the family. Men were heads of households, and their firstborn sons were known as the “firstfruits” of the father’s “strength,” an image in which the man’s offspring are like a bountiful field and the firstborn the firstfruits of that field’s harvest (Gen. 49:3; Pss. 78:51; 105:36). And, since the firstfruits were especially valuable (Num. 18:12), to describe firstborn sons with such language speaks to their special worth (cf. Mic. 6:7; Zech. 12:10).

Second, being the firstborn meant having a special role. Firstborns were to be “preeminent in dignity and preeminent in power” (Gen. 49:3), since they were responsible to maintain the well-being of the household and its honor.123 This explains why they received a double inheritance, known as the “right of the firstborn” (Deut. 21:17), since resources were needed in order to carry out this role. It also meant they had to learn the father’s business and would “serve” him during his life, which is the focus here: “Let my son go that he may serve me” (Ex. 4:23). They are no longer to “serve” Pharaoh as slaves but to “serve” Yahweh as sons.124 How so?

On the one hand the word “serve” in this context describes worship (cf. comment on 3:11–12). Moses’ later requests to Pharaoh can substitute the word “serve” with “hold a [religious] feast to” the Lord (5:1; cf. 10:9, 24–26) or “[make] sacrifice to the Lord” (5:3). At the same time, when used in combination with Israel’s description as “firstborn son,” the word “serve” evokes the larger social background just named: Israel is to obey the Lord in all of life, maintaining the Lord’s honor in this world.

The above also means that to harm Israel, or even to prevent him from serving his heavenly Father, is beyond serious. (We might consider how wrong it would seem to us if someone came and took away and enslaved our child.) The threat is therefore most serious as well: the death of Egypt’s firstborn sons. As the story unfolds the fulfillment of this threat is delayed. The Lord warns Egypt repeatedly about its wickedness, sending nine different plagues, like warning shots across the bow, but to no avail. This leads finally to the last plague, a shot now aimed at the ship’s very heart: those who have refused to release Israel, the Lord’s firstborn son, will lose their own—through death (4:23).125

But this punishment raises serious ethical questions for some. Is it not unjust to single out the firstborn for death? Why not just kill Pharaoh himself? Any answers to these questions must begin by acknowledging the difficulty most feel regarding them. This passage is hard, even painful, for many. Personally, I have wrestled with this passage over the years more than almost any other in the Bible. How do we square this story with the biblical teaching that God is good?

In surveying the various approaches taken, I have found it helpful to begin with two steps.126 The first is to remember that the term “firstborn” in general refers to birth order, not age, meaning it would refer to refer to any firstborn, including grown sons who were mature adults. The second is then to discuss separately the firstborn old enough to be morally culpable and the firstborn too young to be morally culpable. I begin with the firstborn old enough to be morally culpable and make four observations.

First, guilt for this situation cannot be isolated to Pharaoh.

It would seem reasonable to suggest that . . . Pharaoh was hardly the only guilty party in the oppression of the Israelites. His order had to be carried out throughout the entire land, and this required the willing cooperation of his own court officials, regional administrators, military general officers and lesser officers, and civilians of all ranks and types.127

Pharaoh might have been most guilty, but the nation helped (just as Hitler might have been most guilty, but the nation helped). This was a guilt problem for Egypt as a whole, including mature firstborn sons.

But why make them the focus of the judgment? This leads to the next three observations: targeting the firstborn was a display of God’s sovereignty, a punishment corresponding to the crime, and an act of judgment tempered by mercy. In terms of God’s sovereignty firstborn sons were known as the firstfruits of someone’s strength (Gen. 49:3; Pss. 78:51; 105:36), representing the household’s vitality and, as the future head of the household, its very heart. To kill the firstborn of a nation is thus to proclaim God’s sovereignty over its very existence. By this plague the Lord thus displays his sovereign power over the heart of Egypt’s own strength (its firstborn) and his sovereign ability to deliver his own firstborn, the nation of Israel (Ex. 12:12; 13:14–16; Pss. 78:51; 105:36; 135:8; 136:10).

In terms of this being a punishment corresponding to the crime, because Israel was the Lord’s own firstborn son, the punishment comes upon Egypt’s firstborn sons. This would bring home to Egyptians, in the most personal of ways, the nature and severity of their wrong.

And yet, while the Egyptians would have experienced this as incredibly painful, it was judgment tempered by mercy. Whereas the Egyptians were trying to wipe out all Israelite males (Ex. 1:22), the Lord focused on the Egyptian firstborn, a much smaller number. The loss was still incredibly severe, but the judgment was targeted, not indiscriminate like the Egyptians’ attempts.

This leaves the more difficult issue of the firstborn not old enough to be morally culpable for the wrongs done to Israel. I have found it helpful here to distinguish between temporal judgment and eternal destiny. The death of the firstborn was clearly the former; they died as a sign of God’s judgment on the sin of Pharaoh and Egyptian society, even if they did not participate in the community’s wrongs. The same happens elsewhere in punishments brought on a community: when the Lord punished Israel with defeat in war and exile for the sin of its society, many Israelite children would have died that were innocent of the wrongs that led to the punishment. The death of these covenant children in the community’s temporal judgment did not mean they would suffer eternal judgment. Rather, their death only brought them sooner into the joys of heaven itself. In short an important distinction exists between temporal judgment and eternal destiny. In Exodus the former is the focus, not the latter. And, while the Bible nowhere addresses the eternal destiny of children who die outside of the covenant community, I find myself at this point remembering the question of Abraham: “Shall not the Judge of all the earth do what is just?” (Gen. 18:25). And I rest in that.

4:24–26 At first glance the next episode is one of the most curious in Exodus (and, some would say, the entire OT). The text leaves much unsaid, leading to a wide range of opinions concerning its meaning.128 Most agree that the Lord seeks to kill Moses (Ex. 4:24) and that Zipporah’s actions save him (vv. 25–26). But what is the connection between the two? And why does the Lord seek Moses’ death in the first place?

Circumcision is central to this story (v. 25). Earlier, the Lord had commanded Abraham to circumcise his sons as the covenant sign, a sign that was to be applied throughout the generations (Gen. 17:10–13). All those who were not circumcised were considered covenant breakers and were to be cut off from the Lord’s people (Gen. 17:14). That Moses’ son—presumably his firstborn (cf. Ex. 4:25 with 2:21–22)—is not circumcised puts Moses in the same position as Pharaoh: just as Pharaoh is withholding firstborn son Israel from the Lord by not releasing him (4:22–23), Moses is withholding his firstborn son from the Lord by not applying to him the covenant sign. That the Lord seeks Moses’ death underscores the wrong’s severity (and is a warning to all Israelites to be sure to raise their children in the Lord’s covenant). It also explains why Zipporah’s action saves Moses, since she immediately resolves the problem by applying the covenant sign to their son.

While not all agree with the approach just named, the diversity of opinion increases tenfold when we ask, “But why does Zipporah touch the foreskin to Moses’ feet129 and describe him as a ‘bridegroom of blood’ (vv. 25–26)?” Here one is on much shakier ground, as it seems that answering these questions with any degree of certainty requires background knowledge the text assumes but does not state. To the second question one may note that verse 26 implies this saying to be well-known among Israelites. Its meaning, however, remains mysterious, as does the action accompanying it, and the preacher or teacher would do well to avoid building any points of application on proposed answers to these two specific questions.

4:27–28 While Moses is headed from Midian to Egypt, the Lord commands Aaron to meet him in the wilderness (v. 27a). They meet at the mountain of God—Mount Sinai (cf. comment on 3:1–3)—and Aaron gives him a typical family greeting (4:27b; cf. Gen. 29:13; Ex. 18:7). Since Aaron is to be Moses’ spokesman (4:15–16), Moses conveys to him the Lord’s words and also the signs he is to perform to certify the Lord has sent him (v. 28; for the latter, cf. 4:1–9).

4:29–31 Returning together to Egypt, Moses and Aaron gather the Israelite elders (cf. 3:16), who represent the people, and Aaron declares the Lord’s words to them and performs the signs (4:29–30), the latter perhaps at Moses’ command (cf. 7:9–10, 19; 8:5–6). The people see and believe and are able to hear that the Lord has taken favorable note of them (cf. note 102 within comment on 3:16–22 for this sense of “visit”) and understands their affliction (4:31a; cf. 3:7–9, 16). Appropriately, they bow in homage and worship the Lord (4:31b). As noted in the Section Overview, this leaves the reader with a sense of unity and faith among God’s people—a unity and faith soon to be sorely tested.