이사야 18:5 미슈나 참조: Mishnah Chullin

If he chopped off the head with one stroke, the slaughtering is invalid. He was slaughtering and he cut through the neck with one stroke, if the knife was as long as the neck, the slaughtering is valid. If he was slaughtering and he cut off two heads at the same time, if the knife is as long as the neck it is valid. When is this so? When the slaughterer moved the knife forward and not backward, or backward and not forward; but if he moved the knife to and fro, however small it was, even if it was a scalpel, the slaughtering is valid. If a knife fell down and slaughtered [an animal], even though it slaughtered it in the proper way, the slaughtering is invalid, for it is said, "And you shall slaughter and eat," that which you slaughter, you may eat. If [while slaughtering] the knife fell and he picked it up, if his clothes fell and he picked them up, if he sharpened the knife, or if he got tired and his friend came and [continued] slaughtering, if he delayed the time that it takes to slaughter, it is invalid. Rabbi Shimon says: if he delayed the time it takes to examine the slaughtering.