Kelim, Chapter Twenty-Seven, Mishnah Twelve
1) [A piece of cloth] three [handbreadths] square that was torn: if he put it on a chair, and his skin touches the chair, it is pure;
a) And if not, it remains pure.
2) [A piece of cloth] three [fingerbreadths] square one thread of which was worn away, or in which a knot was found, or in which two threads ran alongside each other, is pure.
3) [A piece of cloth] three [fingerbreadths] square that was thrown on the rubbish heap becomes pure.
a) If he brought it back, it it becomes susceptible to uncleanness.
4) Throwing it away always renders it pure and taking it back renders it susceptible to uncleanness, except when it is of purple or fine crimson.
5) Rabbi Eliezer says: a patch of new cloth is also subject to the same law.
6) Rabbi Shimon says: all these materials become pure; they were mentioned only in connection with the return of lost property.
Section one: The piece of cloth described here is torn, but has not yet been completely torn into two pieces. Therefore, we need a test to determine whether or not it is still considered one piece of cloth such that it should be susceptible to midras impurity. If when one puts the cloth on a chair and then sits on the chair, one’s skin touches the chair, the cloth is considered as if it had been torn completely, and it is not susceptible. If the cloth does block his contact with the chair, then it is considered to be whole and is still susceptible to impurity.
Section two: The piece of cloth here is exactly large enough to be susceptible to impurity, but in some way something is awry with one of the strings. Either one of the strings was worn out, or a knot was found in one of the strings, or two of the strings ran parallel and not opposed to each other, as is supposed to be the case in woven garments. In all of these cases the cloth is considered to be smaller than three fingerbreadths and therefore it is pure.
Section three: Throwing away a small piece of cloth renders it pure because it is no longer considered of use. Taking it back renders it again susceptible.
Section four: There are two exceptions to the rule in section threepurple and fine crimson cloth. Since these are such expensive materials, even throwing them away does not render them free from uncleanness.
Section five: Rabbi Eliezer says that the same exception applies to a new piece of cloth. Since it is new, it is more important and even throwing it away does not render it free from impurity.
Section six: Rabbi Shimon disagrees with the anonymous opinion in section four. All material is free from impurity when it is thrown into the garbage heap. However, there is a difference between purple and crimson cloth and regular cloth in that if one finds the former in the trash heap he must announce that he has found them in an attempt to find the owners. The assumption is that no one would throw away such fine cloth. But if one finds a piece of regular cloth in the trash heap, one can assume that it was intentionally thrown away and he may keep it.