Yitzchak is born

Sarah Gives birth to Yitzchak who is the fulfillment of Zerah. On the eighth day of Yitchak’s life, Avraham perform’s Brit Milah on him. Now that Yitchak is born, Yishmael is officially pushed aside. His whole life, he was brought up as Avraham’s son and as the fulfillment of Zerah, but he is no longer in the ‘first place’ position. Avraham now has a second son. Yishmael has learned that he is no longer the fulfillment of the promise.