Keilim 18:9-19:1

Keilim 18:9

If half of a bed (i.e., a long side, a short side and two legs) was stolen or lost, or if brothers or partners divided the bed between them, it is rendered ritually clean. If it was reassembled, it becomes susceptible to ritual impurity from that point on. Rabbi Eliezer says that a bed only contracts impurity as a unit and is purified as a unit; the Sages say that it can contract impurity in pieces and be purified in pieces.

Keilim 19:1

Let’s say that someone dismantles a bed in order to immerse its pieces in a mikvah. One who touches the ropes remains ritually clean. The ropes are considered a part of the bed as soon as three rows of grids have been woven. One who touches from the knot inward is rendered ritually unclean but one who touches from the knot outward remains clean. As far as the loose ends of the knot, one who touches a part that is necessary (for the knot not to come undone) is rendered unclean. Rabbi Yehuda says three fingerbreadths is what’s necessary for this purpose.