Genesis Genesis 25:19-34
Two boys crush each other in the womb of Rebekah, an oracle inverts primogeniture before they are born, and a bowl of red stew costs Esau the birthright. The Septuagint of Genesis 25:23 becomes the verbatim five-word election text Paul quotes at Romans 9:12; the closing Hebrew verb of contempt at Genesis 25:34 returns at Obadiah on the nation Esau fathered.
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.