וזכרתי את בריתי יעקב ואף את בריתי יצחק ואף את בריתי אברהם אזכר
Rashi observes that zechirah, remembering, is mentioned concerning Avraham Avinu and Yaakov Avinu – but not in connection with Yitzchak Avinu. He explains that Yitzchak’s “ashes” (His ashes are considered to be as they would have been if the Akeidah had occurred, and Avraham had offered his son, Yitzchak, on the altar as a korban, sacrifice, to Hashem) are piled up on the Mizbayach. Remembering applies to something which is no longer extant. Yitzchak’s ashes are present. Thus, the term “remembering” does not apply concerning him. Anyone reading this should immediately wonder how the concept of forgetting applies to Hashem….
