Yoreh Deah Siman 18 Seif 6

 

ו סַכִּין חַדָּה שֶׁהֻשְׁחֲזָה, וַהֲרֵי אֵינָהּ חֲלָקָה אֶלָּא מַגָּעָתָהּ כְּמַגַּע רֹאשׁ הַשִּׁבֹּלֶת שֶׁהוּא מִסְתַּבֵּךְ בְּאֶצְבַּע, הוֹאִיל וְאֵין בָּהּ פְּגָם שׁוֹחֲטִין בָּהּ

 

Seif 6

 

When a knife has been sharpened, but its edge

is not smooth, instead, when one touches it, it is like touching the tip of an ear of grain which becomes stuck on one’s finger, [nevertheless,] since it does not have a blemish, one may slaughter with it.