משנה על ביצה 1:2

A sandal, one of whose holes was broken but was then fixed, retains its midras uncleanness. If a second hole was broken and it was fixed, it is free from midras uncleanness but is unclean from contact with midras. If the second hole was broken before the first could be mended, it is clean. If its heel was torn off, or if its toe-piece was removed, or if it was torn in two, it becomes clean. A heel-less slipper that was torn anywhere becomes clean. A shoe that was damaged becomes clean if it cannot contain the greater part of the foot. A shoe that is still on the last: Rabbi Eliezer says: it is insusceptible to uncleanness, But the sages say that it is susceptible. All water skins whose holes have been tied up are insusceptible to uncleanness, except for Arabian ones. Rabbi Meir says: if they are tied up for a while, they are clean; but if they are tied with a permanent knot they are unclean. Rabbi Yose says: all tied up water skins are clean.

If one cut off from any of these a piece one by one handbreadth it is susceptible to uncleanness. [If one cut off a one by one handbreadth piece] from the bottom of a basket it is susceptible to uncleanness. If one cut off from the sides of the basket: Rabbi Shimon says that it is not susceptible to uncleanness, But the sages say one who cuts off a square handbreadth from anywhere, it is susceptible to uncleanness.