Central to Yahweh’s covenant relationship with Abraham is the promises of land and offspring. The land is dealt with first in chapters 12-15, where it is clear the Canaanites will be removed from the land and it will be given to Abraham and his offspring (12:6-7); the destruction of Sodom and Gomorrah being the first fruits of this promise. This explains Yahweh’s speech in 18:17-21, where He tells Abraham of his plans for these cities precisely because Abraham’s offspring will inhabit this land and will need to understand that holiness is essential to maintaining possession.
Though it is promised at the beginning of his story (12:1), it is not until the end that Abraham attains any portion of the land, and a small piece, even then, for his and Sarah’s burial (23:17-18) near the trees of Mamre (23:17). That Abraham never fully realizes this promise is reinforced by the narrators’ repeated reference to the land as “Canaan,” though Abraham has lived there for years (12:5, 13:12, 16:3, 17:8, 23:2 & 19). However, it cannot be ignored that Abraham is staking a claim for himself and Yahweh through the land when he builds altars to Yahweh and calls on Yahweh’s name (12:8), and plants trees (21:33).
A second feature in Yahweh’s covenant is the promise of offspring, dealt with in chapters 16-24. The offspring promise evades fulfillment for a number of years after the initial promise is made. Yet Abraham righteously believes God will fulfill what He has resolved to do pertaining to the promise of progeny (15:16).
Offspring and ancestry play vital roles in the narrative as the means by which a person might live on after they die. Abrahamic religion has no concept of eternal glory or damnation; both are restricted to this life. His offspring, then, assist Abraham in seeing himself as part of a larger narrative Yahweh is developing; a narrative extending beyond him into a larger cosmic plan (12:3).
So, the promise of offspring also highlights the importance of family. The idea of an autonomous individual is entirely absent. Indeed, the text views independence and self-seeking as negative. The prime example of this being Lot’s self-serving decision to choose the beautiful plains of Jordan (13:10-11), which ultimately costs him his wife, his home and the purity of his family line (19:36).Yet even when he violates this norm, a sense of familial responsibility (12:17) and obligation (14:10-16) arises in the clan. Such family solidarity is not even not broken in death (25:8).
 Trees appear frequently in these narratives, often in association with the building of altars (13:18) or an appearance of Yahweh (18:1). Though the mentioning of them is unexplained and ambiguous, they probably symbolizing permanence and ownership over a land where he roams as a transient nomad, a transience which can be endured, however, as the land is a promised, perpetual possession (17:8).
 I find it particularly interesting that Abraham goes to be with his fathers, when it was his fathers that he was originally called forth from. Abraham’s ancestors were probably polytheists, but whatever life-after-death theology there is in the Abraham narratives, it seems to include those who do not follow Yahweh. Unless, of course, this phrase is to be taken as idiomatic.