Shatnez

From Halachipedia
  1. Sitting on Kilayim (linen and wool) is permitted from the Torah but is rabbinically forbidden.[1]
  2. It is permitted to sit on kilayim that is tough and not soft if one’s skin doesn’t touch the kilayim directly.[2]
  3. It is permitted to sit on kilayim cushions under 3 conditions: 1) the cloth the cushions are made from is tough and not soft, 2) it is firmly mounted on a seat and won’t rise up to surround the person, and 3) a person’s skin doesn’t touch the kilayim directly.[3]

Sources

  1. The Gemara Beitzah 14b explains that the Torah only forbids wearing kilayim but not sitting on it. However, rabbinically it is forbidden since a strand of the cloth might come upon a person. Rashi (s.v. shema in his first explanation) adds that if a strand were to come upon a person it would heat him up and be considered a form of wearing kilayim. The gemara further forbids sitting on ten mats one on top of the other with kilayim being the bottom one.
    • The Tosfot Niddah 61b s.v. lo holds that if the kilayim is the type of cloth that you wouldn’t come to wear it is permitted to sit on kilayim as long as you aren’t touching the kilayim directly. This is also the opinion of the Rash (Kilayim 9:2) and Ran (Beitzah 7a s.v. elah kach). However, the Rambam (as understood by the Bet Yosef YD 301:1) argues that it is forbidden. Shulchan Aruch YD 301:1 rules like the Rambam.
  2. The Mishna Kilayim 9:2 says that there’s no issue of kilayim on a pillow or blanket as long as one’s skin doesn’t touch them directly. Tosfot Pesachim 40b s.v. lo understands this to mean that pillows and blankets don't usually have strands that wrap around a person when sat upon. Tosfot Yoma 69a s.v. kashin agrees. The Rambam (Kilayim 10:13), however, learns from here that it is permitted to sit on kilayim if it is tough and one’s skin doesn’t touch the kilayim. The proof for this is the Gemara Beitzah 15a. Similarly, Ran Pesachim 40b s.v. beged quotes this from the Yerushalmi explaining that the pillows and blankets are permitted when they're tough and in that case there's no concern that a strand will come upon one's body. Tosfot Yoma 69a s.v. kashin quoting Rabbenu Tam, the Rosh (Niddah 9:20), Meiri Pesachim 40b s.v. beged, Tur and Shulchan Aruch Y.D. 301:2 agree with the Rambam.
  3. Pitchei Teshuva YD 301:1 citing the Panim Meirot