Before we blow the shofar on Rosh Hashanah, we recite Psalm 47, which includes the words “G‑d shall be exalted with the blast; the L‑rd, with the sound of the shofar.” The psalm concludes with the words “The volunteers of the peoples have assembled, the people of the G‑d of Abraham . . .”

Another psalm in which the shofar figures prominently is Psalm 81, which is part of the Rosh Hashanah Musaf service. Following the words “Sound the shofar on the New Moon, on the appointed time for the day of our festival,” we read, “For it is a statute for Israel, the judgment of the G‑d of Jacob, as a testimony for Joseph . . .”

These two psalms associate the blowing of the shofar with our forefathers Abraham, Jacob (also known as Israel) and Joseph.

It is appropriate that these three great men are associated with the shofar. After all, Rabbi Eliezer1 teaches that both Abraham and Jacob were born in the month of Tishrei, and Joseph was released from Pharaoh’s prison on Rosh Hashanah itself.2

Who is conspicuously missing from this list? Isaac, the son of Abraham and the father of Jacob. In addition to not being mentioned in the shofar-related verses above, the Talmud tells us that, unlike his father and his son, he was not born at this time of year, but in the Passover season.

And yet, we know that Isaac has a strong connection to Rosh Hashanah. In fact, the Torah readings of the day center around his miraculous birth and his near-death upon Mt. Moriah. So why is he absent in the verses from Psalms? And why was he not born at this time of year like his father and son?

Rabbi Levi Yitzchak Schneerson explains as follows:

The Kabbalists associate Isaac with the attribute of gevurah (translated as “strength” and “severity”). If he were to have been born during this time of judgement, there would be too much severity and no room for clemency.

But although Isaac was not born during this time, he is still represented on Rosh Hashanah by the shofar. The shofar, which is usually a ram’s horn, is reminiscent of the ram that appeared just as Abraham was about to sacrifice Isaac upon the altar. This ram then substituted for Isaac as Abraham’s sacrifice. On Rosh Hashanah, the plaintive call of the shofar acts to sweeten the severity of G‑d’s judgment and draw divine kindness and life upon all of creation on this Day of Judgement.

Isaac is the quintessence of Rosh Hashanah.

This notion is reflected in the following gematria (numerical value): The name Abraham equals 248, Jacob is 182, and Joseph is 156. When you add them together, you have 586—the numerical value of the word shofar, which represents Isaac.