Genesis 17:15-27
Same theophany, second petuchah. Gen 17:15-27 names what Gen 17:1-14 inscribed. Sarai becomes Sarah; Abraham laughs inwardly at the announcement and the child is named for the laugh; God says aval - truly - and the covenant narrows from Abraham's seed generally to one named son not yet conceived. Ishmael receives the creation-mandate blessing every nation can receive; Isaac receives the berit olam. At Mamre the angel will quote this annunciation back: shall a word be impossible with God? Luke quotes the angel back over Mary. The child's name is the disbelief converted into gift, and the seed-bearer is the woman God blesses by name.
Genesis 11:10-32
The Babel-builders said na'aseh-lanu shem — let us make for ourselves a name. Eight verses later the text answers them with a different shem entirely: eleh toledot Shem — these are the generations of Shem. The line through which the name-promise will travel is literally called Name. Ten generations descend from that line, then narrow into the toledot of Terah and stop in Ur Kasdim with a barren wife, an idol-serving father, and a brother dead in the family's birth-land. Out of those three impossibilities YHWH calls one man into a moledet he must leave for a patris he must seek.