Halakhah sa Levitico 12:3: Mishneh Torah, Circumcision, Shulchan Shel Arba, Sefer HaChinukh & Mishneh Torah, Positive Mitzvot

Circumcision is an affirmative precept, the neglect of which entails the penalty of excision, as it is said, "And the uncircumcised male who is not circumcised in the flesh of his foreskin—that soul shall be cut off from his people" (Gen. 17:14). It is a duty incumbent upon the father to circumcise his son, and upon the master to circumcise his male slave, whether "born in the house" or bought with money. If the father or master failed to perform the circumcision, he has neglected the fulfillment of an affirmative precept but has not incurred the penalty of excision, to which only the uncircumcised person is made liable. In such case of neglect, the court is charged with the duty of circumcising the infant or slave at the appointed time, and must not leave any male uncircumcised among the Israelites or their slaves.

A proselyte must, before he can enter the communion of Israel be circumcised. If, while still a gentile, he had already been circumcised, it is requisite to draw a drop of blood from the membrum, on the day when he is received, as a sign of the covenant. Similarly, if a male infant is born with the prepuce absent, it is requisite to draw a drop of blood from the membrum when the infant is eight days old. An androgyne that has both male and female organs is to be circumcised on the eighth day. So too a male infant delivered by the Caesarean operation, or one born with two foreskins is to be circumcised on the eighth day.

Circumcisions are only performed during the daytime after sunrise, whether the operation takes place on the eighth day, the regular time, or subsequently, from the ninth day and further on, as it is said "on the eighth day" (Gen. 17:12) i.e. by day, and not at night. If the circumcision takes place after daybreak, it is correct. The whole of the day is proper for circumcision. Still it is a duty to perform it in the early part of the day, for the zealous fulfill their religious obligations at the earliest possible time.