Kelim, Chapter Twenty-Seven, Mishnah Four
Today’s mishnah deals with a person who takes a piece of one of the materials mentioned in mishnah two and cuts off a swatch one handbreadth by one handbreadth in order to sit on it.
1) If one cut off from any of these a piece one by one handbreadth it is susceptible to uncleanness.
2) [If one cut off a one by one handbreadth piece] from the bottom of a basket it is susceptible to uncleanness.
3) If one cut off from the sides of the basket:
a) Rabbi Shimon says that it is not susceptible to uncleanness,
b) But the sages say one who cuts off a square handbreadth from anywhere, it is susceptible to uncleanness.
Section one: If one takes a piece of cloth, leather, sack-cloth or matting and makes a one square handbreadth swatch in order to sit upon it, it is susceptible to midras impurity. The sages provided minimum measures which a piece of cloth needs to be to be susceptible, but only in cases where the cloth was not meant for a seat.
Section two: The same rule applies if one cuts off a piece of material from the bottom of a basket.
Section three: There is a debate over whether a one square piece cut from the sides of the basket is susceptible. Rabbi Shimon holds that it is not. Albeck proposes that the sides of the basket are curved and not good for sitting, unless he reshapes the material. Therefore, simply cutting a piece from the sides to sit upon does not make it susceptible to uncleanness. The other sages disagree and say that even a piece cut from the side is susceptible.