סימן ט – השוחט בסכין מלבנת,
Siman 9
One who slaughters with a knife that is white with heat
א
אִם שָׁחַט בְּסַכִּין מְלֻבֶּנֶת, שְׁחִיטָתוֹ פְּסוּלָה; וְיֵשׁ מַכְשִׁירִין
Seif 1
If one slaughters with a knife that is white (hot) the slaughter is invalidated, although some opinions hold the slaughter may be kosher.