“Abram said: Behold, to me You have not given offspring, and a member of my household is my heir” (Genesis 15:3). “Abram said: Behold, to me You have not given offspring” – Rav Shmuel bar Rav Yitzḥak said: [Abram said to God:] My astrological constellation is pressuring me and saying to me: Abram, you will not beget offspring. The Holy One blessed be He said to him: ‘Indeed, it is as you say; Abram will not beget offspring, but Abraham will beget offspring. “Sarai your wife, you shall not call her name Sarai” (Genesis 17:15) – Sarai will not bear children, but Sarah will bear children.’