Why Circumcision Is on the Eighth Day: The Hidden Meaning Behind the Covenant of Avraham

The commandment of circumcision (brit milah) is to be performed on the eighth day after birth. Medically, it is indeed the ideal day, as on the eighth day, the baby’s blood-clotting factors, particularly vitamin K and prothrombin, reach optimal levels for healing. Beyond medical wisdom lies a deeper question: Why the number eight?

The Torah’s commandments shape creation, and not the other way around. Why did God specifically command that the covenant be made on the eighth day?

The Significance of the Eighth Day

The Torah emphasizes this timing so strongly that circumcision overrides the Sabbath. Normally, the Sabbath, which includes both positive (“Do…”) and negative (“Do not…”) commandments — and whose violation carries the severest penalties, is not set aside even for other mitzvot. But here the verse says, “On the eighth day”, meaning even if that day falls on Shabbat.

This indicates that the covenant of the eighth day holds a holiness that transcends even the sanctity of Shabbat itself.

The Teaching of Rabbi Leib Mintzberg

Rabbi Leib Mintzberg offers a profound insight: Avraham himself was not commanded to circumcise specifically on the eighth day — but rather, not before the eighth day.

Before the baby has lived a full seven days, he is not yet considered a complete human being. Only on the eighth day — after experiencing the full rhythm of one week of creation, does he fully join the cycle of human life.

(Interestingly, even an animal cannot be offered as a sacrifice before eight days old: “For seven days it shall remain with its mother, and from the eighth day onward it may be offered.” — Vayikra 22:27.)

Avraham, in his zeal, performed the circumcision as soon as possible, but his descendants from Yishmael and Keturah did not continue this precision; they circumcise at thirteen years old, following the age of Yishmael.

After Sinai: The Covenant Beyond Time

After the Giving of the Torah, the law was set that circumcision must be done specifically on the eighth day, and even supersedes Shabbat.

To delay entry into the covenant would be, in essence, a defiance of Avraham’s eternal bond with God. The eighth day symbolizes connection beyond the natural order — beyond the seven days of creation, linking the child directly to the infinite.

However, there is an exception: a child born through cesarean section (called “yotzei dofen” in the Talmud) is not circumcised on Shabbat.

Why a Cesarean Birth Is Different

Rabbi Mintzberg explains that the timing of a natural birth is heavenly — it is God who decides the exact moment a child enters the world, whether slightly early or late. That divine timing sanctifies the child’s eighth day, marking it as the appointed time to enter the covenant.

In the case of a cesarean, where the birth was humanly initiated, even with the best intentions, the moment of birth is not divinely determined in the same way. Thus, that day does not carry the same holiness that would warrant overriding the Sabbath.

Nevertheless, Rabbi Chaim of Brisk (Rav Chaim Soloveitchik) writes that although a cesarean-born baby is not circumcised on Shabbat, the mitzvah of performing the brit on the eighth day still applies — it simply does not take precedence over the holiness of the Sabbath.