Genesis 25:19-34 introduce the whole Jacob and Esau saga. [source][source][source]
In the first pericope ( Genesis 25:19-26) we have the record of God answering Isaac"s prayers by making Rebekah fertile (blessing). He gave her two sons, Esau and Jacob, and foretold that from them two nations would come with the elder serving the younger. [source][source][source]
The emphasis of this section is on the divine oracle ( Genesis 25:23) as is clear from the chiastic structure of the narrative. [source][source][source]
"AIsaac was forty years old when he took to wife Rebekah ( Genesis 25:20).BRebekah was barren; prayer for children was answered ( Genesis 25:21 a).CHis wife Rebekah conceived ( Genesis 25:21 b). The children struggled together within her ( Genesis 25:22 a).DRebekah asks for an oracle ( Genesis 25:22 b)D"Yahweh grants her an oracle ( Genesis 25:23)C"Her days to be delivered were fulfilled ( Genesis 25:24 a). And behold, there were twins in her womb ( Genesis 25:24 b).B"Jacob and Esau are contrasted in birth and appearance ( Genesis 25:25-26 a).A"Isaac was sixty years old when Rebekah bore the twins ( Genesis 25:26 b)." [1][source]
The question of an heir continues primary in this section. Who will be Isaac"s heir through whom God will fulfill His promises? Rebekah, like Sarah, was barren ( Genesis 25:21). After20 years of waiting and praying ( Genesis 25:21-22) God gave her children. Which of these two sons would be the blessed heir? God intervened to announce His foreordained choice ( Genesis 25:23). Jacob"s reactions to his election over Esau were quite different from Isaac"s reactions to God"s choice of him as Abraham"s heir, as this section begins to illustrate. [source][source][source]
Scripture does not give the reason God chose Jacob over Esau. What we do know is that His choice did not rest on the superior merit of Jacob but on the sovereign prerogative of Yahweh ( Romans 9:10-13). In ancient Near Eastern culture the first-born normally became his father"s heir. So in designating Jacob as Isaac"s heir God sovereignly overruled natural custom by supernatural revelation. The response of the members of Isaac"s family to this revelation demonstrates their faith, or lack of it. However the main point of the narrative is to trace God"s faithfulness and power in bringing to pass what He had promised. [source][source][source]
"The revelation of the Divine will concerning the two brothers ( Genesis 25:23) was evidently no secret. It is clear that both Esau and Jacob knew of it. This fact is in some respects the key to the true interpretation of this incident [2]." [3][source]