Keilim 1:2-3

Keilim 1:2

Higher than the primary transmitters of ritual impurity are a neveila (an animal carcass that wasn’t ritually slaughtered) and water from the para adumah of which there is enough to sprinkle. These convey ritual impurity to a person by carrying so that he conveys it to his clothes by touching them, though these things do not contaminate his clothes if he just touches them.

Keilim 1:3

Higher than these is a man who was sexually intimate with a niddah (a menstruant woman) because he renders the lowest mattress on which he sits as impure as the topmost mattress (on which he sits directly). Higher still is the emission of a zav (a man who has had a particular type of genital discharge), as well as his spit, semen and urine, plus the blood of a niddah, because these convey ritual impurity through both touching and carrying. Higher still is that upon which a zav rides (like a saddle), since this conveys ritual impurity even if the zav sat on a huge rock that had the saddle under it. Yet higher is the bed or mattress upon which a zav sits, since this conveys impurity by touching the same way that it does by carrying. Even higher is the zav himself, since he can convey impurity to a bed or mattress but this bed or mattress cannot convey impurity to another bed or mattress on which it might later be placed.