Chullin 9 - Need to Validate Slaughter After It Is Done
A Torah scholar must learn how to do three things which require effort and practice: signing his name as a judge or witness, slaughtering, and circumcision.
If while slaughtering one paused, this invalidates the slaughter. How long is the pause? Enough to inspect the pipes, that is, the trachea and esophagus, to make sure that the majority of both pipes were cut and that the knife did not leave the area designated for slaughtering.
After slaughtering, he must indeed inspect the pipes as explained above, and if he did not inspect them, the meat is forbidden to eat. Rabbi Eliezer ben Antignos said that it is forbidden as terefah (sick or incorrectly slaughtered animal), but others say that it is forbidden as nevelah (meat that was not slaughtered at all).
What is the argument? Both agree to the principle of Rav Huna, "An animal during its lifetime is in a prohibited state, until it becomes known that it was slaughtered properly. Once it has been slaughtered, it is in a permitted state, unless we know that it became a terefah," but they argue about how far to take its prohibited state.
Art: Benjamin Gerritsz. Cuyp - The Circumcision