How Old Was Isaac?

This week's Torah reading is called "Chayyei Sarah," "The Life of Sarah" but
in fact, it begins with her death. Interestingly, the Torah tells us nothing
of how she died nor anything of the cause of her death.

On the second day of Rosh Hashanah, instead of a sermon we discussed Rashi's
commentary and various midrashic understandings of the Akedah, the Binding
of Isaac. One of the questions we discussed is how old Isaac was at the time
his father almost sacrificed him. The biblical text seems to indicate a
young lad, certainly someone not yet in his teens. But many commentaries
suggest he was 37 years old.

Where does this idea come from? It comes from this week's parasha, at least
indirectly. You might not pick up on this because of the way the weekly
portions are split up, but at the very end of last week's parasha Abraham
and Isaac return home from their sacrificial journey. The very next thing
that happens, at the beginning of this week's parasha, is Sarah's death.
Again there is something of a gap in the text, because we are not
specifically told that the death of Sarah is connected with the Akedah. But
that is what many midrashim suggest. One possibility is that Abraham and
Isaac were not travelling in close proximity, and Abraham arrived first,
alone. Sarah may have had an inkling of what Abraham proposed to do, and
when he came home alone she thought he had in fact sacrificed Isaac and
either killed herself or died of a broken heart. Another midrash suggests
that it was simply hearing of what had transpired that caused her death.

Now, we know from Genesis that Sarah was 90 when Isaac was born and that she
was 127 when she died. If we assume that her death happened immediately
after the Akedah, this makes Isaac 37 years old at the time of the Akedah.