Summary

Talmud (Rodkinson Edition) — Book 1…

How then is it allowed to circumcise any child on the Sabbath? (perhaps it is a miscarriage, and in that event it would be wrongful to inflict a wound in vain) . Said R. Ada bar Ahabha: "We may do so at all events. If it is a regularly born child, the commandment is fulfilled; and if not, no wound is inflicted, but merely a piece of flesh is cut."
Now, then, we have learned in the above Boraitha, that if it be doubtful whether the child was born in the eighth or in the seventh month the Sabbath must not be violated on its account.
Source: Wikisource

Talmud (Rodkinson Edition) — Book 1…

If he performed the circumcision on Sabbath and did not finish it, he simply made a wound and did not perform a commandment; hence he becomes amenable to Karath. R. Papa opposed this: "The circumciser might say, 'I have performed one half of a commandment; come ye and complete the other half. Why should I be punished by Karath?' Therefore if the circumcision was performed on an adult who, excrescences which make it invalid having remained, will not permit them to be removed, he becomes amenable to Karath." This was opposed by R. Ashi: "As for an adult, what news does that impart to us?
Source: Wikisource

Talmud (Rodkinson Edition) — Book 1…

The Sabbath may also be violated on account of a child who was born at a certain time, but not on account of one who was born at twilight (and it is not known whether it was born on Sabbath or on the following day) . It is not allowed to violate the Sabbath on account of a child who was born without a foreskin, because the school of Shamai (only) contends, that even if a child is born without a foreskin, some blood must be drawn in commemoration of the covenant. The school of Hillel, however, says, "That is not necessary."
Source: Wikisource

Get perspective with Kwize: daily news enlightened by great literature