Miszna do Para 12:13

The following hides are susceptible to midras uncleanness: A hide which he intended to use as a rug, A hide used as an apron, A hide used as the lower covering of a bed, A hide used by a donkey-driver, A hide used by a flax-worker, A hide used by a porter, A hide used by a doctor, A hide used for a crib, A hide put over a child's chest, A hide for a cushion. A hide for a covering. All these are susceptible to midras uncleanness. A hide for wrapping up combed wool and a hide worn by a wool-comber: Rabbi Eliezer says it is susceptible to midras, But the sages say that it is susceptible to corpse uncleanness only.