Reference for Chullin 1:2
הַשּׁוֹחֵט בְּמַגַּל יָד, בְּצוֹר, וּבְקָנֶה, שְׁחִיטָתוֹ כְשֵׁרָה. הַכֹּל שׁוֹחֲטִין וּלְעוֹלָם שׁוֹחֲטִין, וּבַכֹּל שׁוֹחֲטִין, חוּץ מִמַּגַּל קָצִיר, וְהַמְּגֵרָה, וְהַשִּׁנַּיִם, וְהַצִּפֹּרֶן, מִפְּנֵי שֶׁהֵן חוֹנְקִין. הַשּׁוֹחֵט בְּמַגַּל קָצִיר בְּדֶרֶךְ הֲלִיכָתָהּ, בֵּית שַׁמַּאי פּוֹסְלִין, וּבֵית הִלֵּל מַכְשִׁירִין. וְאִם הֶחֱלִיקוּ שִׁנֶּיהָ, הֲרֵי הִיא כְסַכִּין:
When a person had cut the throat [of an animal] with a hand sickle, a sharp flint stone, or with a reed, it is Cashér. All may slaughter, at any time, and with any instrument, excepting a reaping hook, a saw, the [sharp] teeth [of animals fixed in the maxillary bone], or with the finger nail, because the [first mentioned three] do not cut, but strangle [and tear]. When a person slaughtered an animal with a reaping hook, having teeth or notches, with the first or down stroke or cut only, it is unfit for use according to Beth Shammai, but Beth Hillel hold it to be Cashér; but if the teeth of the reaping hook had been ground away [so as to give it a sharp and even edge] it is the same as a knife.