Gen 17:12

“And he that is eight days old shall be circumcised among you,.... A son or infant of eight days old; it might not be circumcised before, but for some reasons might be deferred longer. The reasons why this rite was ordered to be performed in infancy, according to Maimonides (d), were, because if it had been deferred to riper age it might have been neglected, and never performed; and because at such an age the pain is not so sensibly felt, by reason of the tenderness of the skin, and the weakness of the imagination; as also because the affections of parents are not then so strong as they are when one year, and especially three or four years old; and particularly it was ordered on the eighth day, because all animals, as soon as born, on account of their great humidity, are very weak, and scarce any other than they were in their mother's womb, until the end of seven days, after which they begin to be reckoned among those that perceive the air of this world; and so he remarks the same is to be observed in beasts, that seven days they were to be with their dam, Exo 22:30. According to the Jewish canon (e),"an infant might be circumcised on the eighth, ninth, tenth, eleventh, and twelfth, neither less nor more; (not less than eight days, nor more than twelve (f);) according to the usual custom on the eighth; if he was born between the two evenings, he is circumcised on the ninth; if between the two evenings of the evening of the sabbath, he is circumcised on the tenth; if on a festival day, after the sabbath, he is circumcised on the eleventh; if on the two days of the beginning of the year, he is circumcised on the twelfth: an infant that is sick, they do not circumcise it until it is well.''Which sickness they interpret not of sore eyes, and the like, but of an ague or fever; and when a child on the eighth day is red or yellow, or a woman has lost her children through circumcision, two or three one after another, then it is deferred; and they reckon seven days from a child's recovery from sickness, and then circumcise it (g); but circumcision on the eighth day was always reckoned most valid and authentic, and according to rule; see Gill on Phi 3:5; and the Jews were careful to do it on the eighth day as soon as they could, though only when and while it was day. Their canon or rule runs thus (h),"they do not circumcise until the sun shines out on the eighth day of a child's birth, and all the day is fit for circumcision; but they that are prepared hasten to the commandment, and circumcise immediately in the morning; and indeed circumcision, which is not in its proper time, is never performed but in the day:''for they observe (i), it is said on the eighth day, Lev 12:3; the day, and not the night. And this was to be done to every man child in your generations; in all succeeding ages until the Messiah came, the end of the law; and when the lease of the land of Canaan, of which this was a seal, would be out; and when the righteousness of faith, it was also a seal of, would come upon the uncircumcised Gentiles: he that is born in the house, or bought with money of any stranger, which is not of thy seed; concerning which Maimonides (k) gives these rules,"a servant is born in the power of an Israelite, and another that is taken from Heathens, the master is bound to circumcise them; but he that is born in the house is circumcised on the eighth day; and he that is bought with money is circumcised on the day that he is received, even if he received him on the day he is born, he is circumcised on that day; if he receives a grown servant of Heathens, and the servant is not willing to be circumcised, he bears with him a whole year, but more than that it is forbidden to keep him, seeing he is uncircumcised, but he must send him again to the Heathens.''No man was to be forced to embrace the true religion, or obliged against his will to submit to its ordinances. (d) Moreh Nevochim, par. 3. c. 49. p. 506. (e) Misn. Sabbat, c. 19. sect. 5. (f) Misn. Eracin, c. 2. sect. 2. (g) Maimon. Hilchot Milah, c. 1. sect. 16, 17, 18. Schulchan Aruch, ib. c. 262. sect. 2. 263. sect. 1, 2. (h) Schulchan Aruch, c. 262. sect. 1. (i) Maimon. Hilchot Milah, c. 1. sect. 8. (k) Ibid sect 3, 6.”

“Days, when he will be able to bear the pain without danger. This might be deferred for a just reason, as it was in the desert, Josue v. 6. In this case people might be saved, as younger children and all females might, by the application of the remedies used in the law of nature, sacrifice, the faith of parents, &c. (Menochius) — Of your stock, and, being arrived at years of discretion, is desirous of enjoying your privileges. Some think, that slaves had no choice left; but servants, and people who had a mind to live in the country, were not bound to submit to this rite against their will. It is even more probable, that none were under this obligation, except Abraham and his posterity by Isaac. His other children adopted it in part, but not with the exactitude of the Jews. (Calmet)”