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. ”
