1 Chronicles 1:28–42 (ESV)

28 The sons of Abraham: Isaac and Ishmael.

The call of Abraham marks a turning point in the sacred history of Israel because it marks the onset of God’s plan to redeem his fallen creation. The focus on Eber has already pointed to the fact that God's plan will involve one who is called a Hebrew. Abraham is already referred to as “Abram the Hebrew” in Genesis 14:13. Moreover, attention is also drawn to the term “seed” in the context of the Abrahamic covenant (see Genesis 12:7; Genesis 13:15–16; Genesis 15:18; Genesis 16:10). This is a clear reference to the “seed” (singular) of the woman who would crush the serpent’s head, noted in Genesis 3:15. This verse has been interpreted as the first gospel promise. The New Testament rightly regards this “seed of the woman” as Jesus Christ, the Saviour (Acts 3:25; Romans 1:3; Romans 4:13, Romans 4:16, Romans 4:18; Galatians 3:16, Galatians 3:19; 2 Timothy 2:8).

The point of this section is quite clear. Abraham’s son Ishmael became the father of a nation, and Keturah gave Abraham many sons. But it is through Jacob (Israel) that the promised line continues.