“The matter was greatly distressing in Abraham’s eyes, regarding his son” (Genesis 21:11). “The matter was greatly distressing in Abraham’s eyes” – that is what is written: “And shuts his eyes from seeing evil” (Isaiah 33:15). “God said to Abraham: Do not be distressed about the lad and about your maidservant; everything that Sarah says to you, heed her voice; for through Isaac will be called your descendants” (Genesis 21:12).
“God said to Abraham: Do not be distressed…[for through Isaac will be called your descendants]” – Rabbi Yudan said: “Isaac” is not written here, but rather, “through Isaac [beYitzḥak].”32Part, but not all, of Isaac, as Esau is not included. Rabbi Azarya in the name of bar Ḥatya: Beit is two – through the one who acknowledges the existence of two worlds. Rabbi Yudan ben Rabbi Shalom said: It is written: “Remember the wonders He has performed, His signs, and the judgments of His mouth” (Psalms 105:5).
You [God] have provided a sign by what You have expressed with Your mouth:33Translation follows version of the text of Etz Yosef. Anyone who acknowledges two worlds “will be called your descendants,” and anyone who does not acknowledge two worlds will not be called your descendants.