3,107. Sitting on Shaatnez

Hilchos Kilayim 10:12

One is permitted to make and sell shaatnez; it is only prohibited to wear or to cover oneself with it, as per Deut. 22:11 – “You shall not wear shaatnez” – and Lev. 19:19 – “A garment of shaatnez mixed materials shall not come upon you.” In order to be prohibited, a shaatnez garment must come upon a person in a manner of wearing. If shaatnez comes upon a person in a manner that is unlike wearing, such as a tent of shaatnez, one may sit under it. Under Torah law, it is likewise permitted to sit on shaatnez bedding, because “shall not come upon you” doesn’t preclude having it under you. Under rabbinic law, however, even if there are ten layers of bedding piled one on top of another, if the bottom layer is shaatnez, one may not sit on the top layer out of concern for shaatnez.

Hilchos Kilayim 10:13

The previous halacha applies to soft materials like curtains and sheets. When it comes to firmer materials that won’t get wrapped around a person, like pillows and cushions, one may sit or lie on them so long as his skin doesn’t touch the shaatnez.