יורה דעה י״חYoreh De'ah 18

Se’if 4ד׳

סַכִּין שֶׁתִּבָּדֵק בְּהוֹלָכָה וְלֹא הִרְגִּישׁ שֶׁיֵּשׁ בָּהּ פְּגָם, וּכְשֶׁהֶחֱזִיר אוֹתָהּ בַּהֲבָאָה הִרְגִּישׁ שֶׁיֵּשׁ בָּהּ פְּגָם, וְזוֹ הִיא הַנִּקְרָא מְסֻכְסֶכֶת, אִם שָׁחַט בָּהּ דֶּרֶךְ הוֹלָכָה וְלֹא הֵבִיא, שְׁחִיטָתוֹ כְּשֵׁרָה; וְאִם הֵבִיא, שְׁחִיטָתוֹ פְּסוּלָה. וְהָנֵי מִלֵּי כְּשֶׁהִרְגִּישׁ בָּהּ קֹדֶם שְׁחִיטָה, אֲבָל אִם מָצָא סַכִּינוֹ יָפָה קֹדֶם שְׁחִיטָה, וְאַחַר שְׁחִיטָה מָצָא בָּהּ פְּגִימָה מְסֻכְסֶכֶת, וְאָמַר: בָּרִי לִי שֶׁלֹּא עָשִׂיתִי אֶלָּא הוֹלָכָה לְבַד, שְׁחִיטָתוֹ פְּסוּלָה. הַגָּה: וְיֵשׁ מַחֲמִירִים דְּכָל מְסֻכְסֶכֶת אֲסוּרָה, עַד דְּקַיְמָא אָרֵישָׁא דְּסַכִּינָא מַמָּשׁ אִם שָׁחַט בְּהוֹלָכָה; וְאַסֵּיפָא דְּסַכִּינָא מַמָּשׁ, אִם שָׁחַט בַּהֲבָאָה (הִלְכוֹת שְׁחִיטוֹת יְשָׁנִים וְהַגָּהות סְמַ"ק וּפוֹסְקִים הַנַּ"ל). וּלְפִי שֶׁאֵין אָנוּ בְּקִיאִין הֵיכָן מִקְרֵי רֵישָׁא דְּסַכִּינָא, יֵשׁ לְהַטְרִיף הַכֹּל (ד"ע גַּם הג"ה בִּשְׁחִיטַת מהרי"ו וכ"מ בְּמָרְדְּכַי וְכָל בּוֹ וַאֲגֻדָּה, וְכֵן כָּתַב הָאָגוּר שֶׁכֵּן הַמִּנְהָג) וְהָכֵי נָהוּג.

A knife that is examined by carrying it forward and he did not feel that there is a notch in it, and when he returned it in the bringing back he felt that there is a notch in it — this is the one that is called a mesukseket (one that slopes away): if he slaughtered with it in the way of carrying forward and did not bring it back, his slaughter is valid; and if he brought it back, his slaughter is invalid. And these words apply where he felt it before the slaughter; but if he found his knife good before the slaughter, and after the slaughter found in it a notch that is a mesukseket, and said: I am certain that I did nothing but carry it forward alone — his slaughter is invalid. Hagah [Rema]: And there are those who are stringent, that every mesukseket is forbidden, unless it stands at the very head of the knife where he slaughtered by carrying it forward, and at the very end of the knife where he slaughtered by bringing it back (Hilchot Shechitot Yeshanim, and Hagahot Semak, and the poskim mentioned above). And since we are not expert in where the head of the knife is called, there is ground to declare it all a tereifah (an animal with a fatal defect) (his own opinion; also the Hagahah in the Shechitot of the Maharyu, and so it is implied in the Mordechai and Kol Bo and Agudah, and so too the Agur wrote, that such is the custom), and so is the practice.

Se’if 5ה׳

סַכִּין שֶׁיֵּשׁ בָּהּ פְּגִימוֹת הַרְבֵּה, אֲפִלּוּ כֻּלָּן מְסֻכְסָכוֹת, אֲפִלּוּ שָׁחַט בָּהּ בְּדִיעֲבַד, פְּסוּלָה. דְּמִתּוֹךְ שֶׁפְּגִימוֹתֶיהָ מְרֻבּוֹת חַיְשִׁינָן שֶׁמָּא הֵשִׁיב יָדוֹ מְעַט וְלֹא הִרְגִּישׁ.

A knife that has many notches in it, even if they are all mesuksakot, even if he slaughtered with it, after the fact it is invalid, for since its notches are many we are concerned that perhaps he drew his hand back a little and did not feel it.