v1-4: Abraham has 6 more children by Keturah, a further indication of God's blessing upon him. Since Sarah is now dead, there is nothing inappropriate in what Abraham does.
v5-6: Isaac is set apart from the other sons. He remains the inheritor of God's promises to Abraham. Abraham also has a number of concubines, and has sons by them.
v7-11: There are 35 years between Isaac's marriage to Rebekah and Abraham's death. We note that the birth of Jacob and Esau preceded Abraham's death; also the dispute between Isaac and Abimelech probably also preceded Abraham's death. This is typical of Jewish writing, which is thematic, rather than chronological. There are three families described; Abraham, Ishmael, and Isaac, starting with the eldest.
Abraham was 'gathered to his people.' According to Jewish tradition, this phrase meant the man had finished his work well, indicating he had lived a godly life..
Isaac lives in Beer Lahai Roi, where God has blessed Hagar; the "well of the One who lives and sees me."
v12-18: There are twelve princes of Ishmael, see 17.20.
Ishmael and Isaac live apart, although they come together to bury Abraham. There is also hostility, fulfilling 16.12. In fact, Ishmael followed the same journey of Hagar, his mother.
v19-22: Isaac, like Abraham, prays for his wife to bear children. Both have to learn to depend on God's mercy and power. Rebekah also enquires of the Lord.
v23: God's overall purpose for the two nations. Jacob's deception later, in stealing Esau's birthright, was not God's purpose, but was with God's permission, see Mal 1.1-5. Here the two principles of divine predestination and human responsibility are intertwined. Both hold true; and we must hold both in tension in our thinking.
v24-26: The birth of the twins, immediately indicating two distinct characters; Esau the hairy, and Jacob the deceiver.
v27-28: Esau and Jacob are always different, even as youngsters. Later their distinctives become animosity. Even Isaac and Rebekah were influenced by this animosity. See 27.5-17, where Rebekah helped Jacob steal Esau's blessing.
v29-34: Esau is the profane person, Heb 12.16, preferring the physical above the spiritual, the temporal above the eternal. Jacob takes advantage of Esau's physical weakness; but is he really so weary that "I am about to die?" Esau, we read, despises his birthright.