1-chronicles 1:28

Isaac and Ishmael - Isaac, though younger than Ishmael, is placed first, as the legitimate heir, since Sarah alone was Abraham's true wife (compare the 1 Chronicles 1:36 note).

1:28 The sons of Abraham - All nations but the seed of Abraham are already shaken off from this genealogy. Not that we conclude, no particularpersons of any other nation but this found favour with God. Multitudes willbe brought to heaven out of every nation, and we may hope there weremany, very many people in the world, whose names were in the book of life,tho' they did not spring from the loins of Abraham.