בראשית, פרק י״ז, פסוק כ״ד

Abraham's circumcision at age ninety-nine serves as a crucial spiritual preparation. By taking place just before the birth of Isaac, the act ensures that his holy offspring would be born into a state of covenantal purity [ביאור יש״ר]. The timing also highlights Abraham's eagerness to fulfill the will of God, as he carried out the instruction on the very day he received it, just before his hundredth year [רד״ק].

Since Abraham observed the laws of the Torah even before they were formally given, a question arises as to why he waited until he was ninety-nine to circumcise himself. The primary approach among commentators is that he intentionally waited for God's explicit instruction, knowing that fulfilling a direct command carries greater spiritual weight than volunteering an action [מזרחי, ריב״א]. Others suggest he simply did not want to wound his body without clear Divine permission [ריב״א]. Waiting until such an advanced age also served to publicly sanctify God's name. It proved to his generation that the procedure was done entirely for God and not for medical reasons, even in the face of public mockery [מזרחי]. Furthermore, before entering this covenant, Abraham still lacked the ultimate spiritual and intellectual perfection required to fulfill the commandments completely [ריב״א, ברטנורא].

When the moment arrived, Abraham acted as both the initiator and the recipient of the physical procedure, either performing it himself or directing others to do it to him [שד״ל, ביאור יש״ר, רש״י, שפתי חכמים]. Because of his advanced age, his flesh was already softened, meaning he required a simpler physical cutting than the more extensive procedure needed for a younger person like Ishmael [ריב״א, ברטנורא]. Although his entire household underwent the procedure on the exact same day, the covenant was fundamentally established with Abraham alone. The rest of his household participated simply because they were under his authority [מלבי״ם].

Beyond the physical procedure, circumcision holds profound spiritual meaning. It stands as a permanent mark in the flesh and serves as one of the three primary commandments—alongside the Sabbath and phylacteries—that testify to faith [רבנו בחיי]. Through the merit of this covenant, the Israelites were promised three eternal gifts: the kingdom of the House of David, the Land of Israel as a lasting possession, and the resting of the Divine Presence among the people [רבנו בחיי]. Finally, it grants profound spiritual protection, saving those who enter the covenant from the severe judgment destined for those who remain uncircumcised in heart [רבנו בחיי, תולדות יצחק].