Shabbos 19:1-2

Shabbos 19:1

If a mohel did not bring a knife before Shabbos, he may bring it on Shabbos, uncovered so that spectators will understand what he is carrying and why. If it is a time of oppression and circumcision is prohibited by the secular authorities, it may be covered with witnesses who will attest as to what it was he carried. Rabbi Eliezer even permits one to cut wood to make charcoal to make a knife. Rabbi Akiva stated a general principle: whatever could have been done on Friday does not supersede Shabbos, while whatever could not have been done on Friday does supersede Shabbos.

Shabbos 19:2

Anything necessary for a bris may be done on Shabbos, including cutting, peeling, suction, bandaging and applying cumin to the wound. If he did not grind the cumin before Shabbos, one may grind it with his teeth and apply it. If one did not mix wine and oil (for use as a topical medication) before Shabbos, he may apply them separately. One may not prepare a sleeve for the infant’s member on Shabbos but one may wrap a strip of cloth around it. If a strip of cloth was not prepared before Shabbos either, one may go even to another courtyard, wrap a strip of cloth around his finger there, and bring it back.