Gen 17:13

“המול ימול יליד ביתך HE THAT IS BORN IN THY HOUSE MUST NEEDS BE CIRCUMCISED — Here the statement that one born in the house must be circumcised is repeated but it does not say “after eight days” as in 5:12, thus teaching you that there are some cases of those “born in the house” who have to be circumcised on the first day of birth, as is explained in Treatise Sabbath (Shabbat 135b).”

“He that is born in thine house, and he that is bought with thy money, must needs be circumcised,.... Or "in circumcising shall be circumcised" (l), shall certainly be circumcised; this is repeated to denote the necessity of it, and what care should be taken that this be done, because there was to be no uncircumcised male among them, Gen 17:10; nor any conversation and communion to be had among them, especially in a religious way. And my covenant shall be in your flesh for an everlasting covenant; circumcision was to be seen in their flesh, and no methods were to be taken to draw over the foreskin again, but it was to continue as long as they lived; and so in their posterity, in all succeeding ages, as a sign of the covenant and promise which should remain until the Messiah's coming. (l) "circumcidendo circumcidetur", Pagninus, Montanus &c.”

“He that is born in thy house - The son of a servant; he that is bought with thy money - a slave on his coming into the family. According to the Jewish writers the father was to circumcise his son; and the master, the servant born in his house, or the slave bought with money. If the father or master neglected to do this, then the magistrates were obliged to see it performed; if the neglect of this ordinance was unknown to the magistrates, then the person himself, when he came of age, was obliged to do it.”