New Defender's Study Bible Notes
15:10 in the midst. God was to confirm the covenant to Abram in a most instructive manner. Though God’s promise had been free and unconditional to Abram (premised only on his faith), it would be very costly to God, requiring the death of His incarnate Son. This was pictured by the death of one of each of the five kinds of clean animals acceptable for sacrificial purposes, with their remains divided into two rows. This was customary procedure at the time in establishing a solemn compact, with the contracting parties sealing it by passing between the two rows. Here, however, only God passed through, since it was a uni-lateral, unconditional commitment on His part.
15:12 a deep sleep. The whole procedure in this remarkable ritual was profoundly instructive to Abram. The long delay foreshadowed a long period that must elapse before God’s promise would be fulfilled, during which the believer would have to guard against attacks of wicked men and evil spirits. The deep sleep could only symbolize death–a substitutionary death by One whom the sacrifices pictured, and in whose death Abram and all believers must share before the glory can follow.
15:13 four hundred years. Some writers take this as a round number, the more precise value being 430 years (Exodus 12:40). But see note on Exodus 12:41.
15:16 fourth generation. It is not absolutely certain whether the 430-year term mentioned in the Abrahamic covenant begins with the coming of Abraham into Canaan or the descent of the children of Israel into Egypt. The former seems indicated by Galatians 3:16-17 in which case the “sojourning” mentioned in Exodus 12:40 and the “affliction” of Genesis 15:13 would apply to their total experience in both Canaan and Egypt. If this is the case, then the actual sojourn in Egypt would be only 215 years (from the time of Abram’s entry into Canaan to the birth of Isaac was 25 years; Isaac was 60 years old at Jacob’s birth; and Jacob was 130 years old when he and his children migrated to Egypt, a total of 215 years–see Genesis 12:4; 21:5; 25:26; 47:9). The “fourth generation” consisted of men whose great-grandfathers had been among the seventy Israelites who entered Egypt. Even if the children of Israel actually stayed 400 years in Egypt, the life span in those days was still around 100 or more (Moses died at 120), so it would have easily been possible for people of the fourth generation still to be living at the time of the exodus.
There is also the problem of whether 215 years could have been enough time for the Israelite population to grow from about seventy to about two million. Although this seems unlikely, it would have been possible if the average family size had been about eight children (remember that Jacob himself had twelve) and the average life span still about one hundred years, with parents living to see their great-grandchildren grow to maturity. In contrast, consider the notes at Exodus 6:17 and 12:41.
15:18 covenant with Abram. Although this is the first time God’s promises to Abram are actually called a covenant, its terms merely confirm and clarify the initial promise in Genesis 12:7. Its ultimate fulfillment is yet future, although it received a precursive and token fulfillment under Solomon (I Kings 8:65) and possibly Jeroboam II (II Kings 14:25).
15:20 the Hittites. The Hittites were descended from Heth (Genesis 10:15), eventually becoming a great empire. See notes on Genesis 23:20 and Joshua 1:4. There are some forty references to them in the Bible.