"Avraham was 99 years old when he circumcised himself. (Gen. 17:24)

Avraham observed all the mitzvot out of great devotion to G-D. But for this mitzvah he waited until G-D told him to do so. A number of commentaries offer explanations why did not circumcise himself sooner, even though he observed all the other mitzvot.

  1. There is a rule that a mitzvah is greater for someone who is obligated to do it than someone who is not obligated. Circumcision is a mitzvah that can only be done once. Therefore, Avraham waited until G-D instructed him to do so.
  2. It is forbidden to injure yourself. Therefore, it would have been a sin to remove his foreskin unless he was specifically told to do so by G-D.
  3. Our rabbis teach that Avraham fulfilled the entire Torah. They meant he fulfilled all the mitzvot after he performed circumcision, when his actions were imbued with the holiness of circumcision. [Avraham was 99 years old at his brit mila. The Hebrew letters for 99 are צ"ט (tzadi tet). The names of these two letters are spelled צדי"ק ט"ת, 90+4+10+100+9+400 = 613, the number of mitzvot in the Torah.]

The Shelah offers his own answer: The Midrash (Braisheet Raba 47:11) tells that people resented the idea that Avraham would circumcise himself. They even had plans to prevent him from doing so. The people knew that circumcision would set apart Avraham in holiness from the other nations. G-D challenged them by having Avraham perform the circumcision at a time when people knew what he was up to.

Therefore, if Avraham would attempt circumcision on his own, he would place himself in danger from people wanting to harm him. It would not be right to rely on a miracle to be protected. Instead, he waited until G-D directed him to circumcise himself, when the decision was out of his hands.