ג
שְׁנַיִם שֶׁשּׁוֹחֲטִין, בֵּין שֶׁאוֹחֲזִין בְּסַכִּין אֶחָד, בֵּין שֶׁכָּל אֶחָד סַכִּינוֹ בְּיָדוֹ, וְנִתְכַּוֵּן אֶחָד מֵהֶם לְשֵׁם דָּבָר הַפּוֹסֵל, הֲרֵי זֶה פְּסוּלָה. וְכֵן אִם שָׁחֲטוּ זֶה אַחַר זֶה וְנִתְכַּוֵּן אֶחָד מֵהֶם לְשֵׁם דָּבָר הַפּוֹסֵל, פָּסוּל. בַּמֶּה דְּבָרִים אֲמוּרִים, כְּשֶׁהָיָה לוֹ בָּהּ שֻׁתָּפוּת, אֲבָל אִם אֵין לוֹ בָּהּ שֻתָּפוּת, אֵינָהּ אֲסוּרָה, שֶׁאֵין אָדָם מִיִּשְׂרָאֵל אוֹסֵר דָּבָר שֶׁאֵינוֹ שֶׁלֹּוֹ, שֶׁאֵין כַּוָּנָתוֹ אֶלָּא לְצַעֲרוֹ.
Seif 3
If two people slaughter the same animal together, whether both grab the same knife in their hands,
or each one slaughters with a different knife simultaneously, if one of them has intention for the sake of a invalidated thing their (Slaughter) is invalidated. Also if they slaughter the same animal one after the other, and one has in mind for the sake of an invalidated thing, (the slaughter) is invalidated.
This only refers to a case where they shared ownership of the animal, however if they did not share ownership, and the one with the improper intent is not the owner, it is not invalidated, because it is impossible for a Jew to cause his fellow Jew’s property to become forbidden to him, and this could only be for the intent of causing him pain, therefore it is inactive.