There is in fact a tradition that Isaac was in fact sacrificed by Abraham.
The Shibbolei HaLeket reports this tradition in these words: “When Isaac was bound on the altar and reduced to ashes and his sacrificial dust was cast onto Mount Moriah, the Holy One, blessed be He, immediately brought upon him dew and revived him”.
Rashi, commenting on verse 16, quotes the Tanchuma which speaks of “the ashes of Isaac heaped up and serving as a means of atonement”. Another version, in the name of Rabbi Shimon bar Yochai, says that if not actually sacrificed, Isaac gave a quarter of his blood as an atonement for Israel.
This is not, however, the general view. Ibn Ezra offers the normative interpretation of the text: though the verse says that Abraham returned, “Isaac is not mentioned because he was under Abraham’s care. Those who say that Abraham slaughtered Isaac and left him on the altar and following this Isaac came to life are contradicting Scripture”, since the Torah explicitly states (verse 12) that God commanded Abraham not to slay Isaac.
The accepted reading of the story is that though Isaac was bound, he was not sacrificed. The story is the Binding of Isaac, not – despite the use of this phrase in Christian literature – the Sacrifice of Isaac.
In Jewish tradition the crucial element is Abraham’s preparedness to obey God and Isaac’s willingness to go along with his father. The intervention of an angel ensures that no harm comes to Isaac.
Abraham Joshua Heschel tells of a teacher who was studying the story with his class and trying to get them to feel a sense of relief when the angel appeared. To the teacher’s surprise, one child, instead of being happy at the arrival of the angel, burst out crying.
“What are you crying for?” asked the teacher; “wasn’t Isaac saved?”
“Yes,” sobbed the child, “but what if the angel had been late?”
What did the teacher say? “It is not angels who are late. People can be late, but angels come on time!”
It is a wonderful vignette, but then there comes the sobering thought that maybe this does not apply to the Holocaust.
It is beautiful to say that angels come on time, and the truth is that God and His angels did finally intervene and arrest the Holocaust… but many will ask, “So why did they not come sooner?” And it is a difficult question.