Beit Yaakov on Torah, Vayera 41/בית יעקב על התורה·וירא מ״א

1And the Lord remembered Sarah, etc. (Genesis 21:1): Behold until this Parashah, it is speaking about the world of chaos; but from this Parashah and onwards, it is speaking about the world of reparation. And for that reason, it is the fourth Parshah, corresponding to the sefirah (emanation) of Eternity (Netzach). For there in the world of chaos, it is written (Genesis 6:6), "And the Lord regretted, etc. and He became saddened to His heart." Whereas this Parashah hints to the sefirah of Eternity - "Moreover, the Netzach of Israel does not deceive or regret, for He is not a man that He should have regrets" (I Samuel 15:29). And for that reason, "And the Lord remembered Sarah, etc.," was also written in this Parashah. That is because the birth of Sarah was also a change in the world. And we read this section on Rosh Hashanah. For there is a change then as well, since every year on Rosh Hashanah, the root of the creation is aroused - as it is found in the holy Zohar (Tetzaveh 184a).