The Abraham cycle (Genesis 11:27–25:11) is a drama of increasing tension—a tension between Yahweh’s promise that Abram would have an heir, indeed, that he would become the father of many nations, and the threat to the fulfillment of that promise by a series of crises. The literary technique employed is what Peter Ellis calls “the obstacle story”:
Few literary techniques have enjoyed so universal and perennial a vogue as the obstacle story. It is found in ancient and modern literature from the Gilgamesh epic and the Odyssey to the Perils of Pauline and the latest novel. Its character is episodal. [The episodes are] not self-contained but find [their] raison d’être in relation to the larger story or narrative of which [they are] a part. [The] purpose is to arouse suspense and sustain interest by recounting episodes which threaten or retard the fulfillment of what the reader either suspects or hopes or knows to be the ending of the story.1
What ties the entire Abraham cycle together is the problem of an heir. Yahweh’s promise of posterity to Abram (Genesis 12:2) highlights the question: Who will be Abram’s heir?