God comes to Abram again and tells him about how Abram's offspring will be "exceedingly numerous." As far as I can tell, this is at least the third time. Does god think that Abram is overly forgetful? Or maybe god is just losing track of who he's told what; after all, if your experience of time is infinite, pinpointing individual moments has got to be something of a challenge!
So God renames Abram to Abraham (according to the footnotes, this is a change from "exalted ancestor" to "ancestor of a multitude") and Sarai to Sarah (no illuminating info for this name change, although some Googling tells me it is "my princess" to "princess"). This, however, is not a big enough symbol of the covenant. No, god also drops the little bomb that every male has to circumcise the flesh of his penis.
I can only imagine what the reaction to that announcement was! No, wait, scratch that, I can picture that it was probably almost exactly like this:
"I don't think I have extra..."
As an interesting note here, god specifically calls out that this circumcision business is required of both Abraham's descendants but also all of the slaves of his household, both the ones born into his house and the ones he buys. Again, a straight up endorsement of slavery (and slave-trading) from a book that some want to use as a springboard of moral authority.
God tells Abraham about the son that he will have, although Abraham is a little skeptical, given that he is 99 and Sarah is 90 at this point. He suggests that Ishmael could be the one through which god fulfills the covenant, but god insists that Sarah will have her own son, although he does consent to toss Ishmael a blessing in the form of fathering 12 princes and a great nation.
Abraham then goes and carries out the circumcision. Yikes. That had to be a bad day in the household!