Keilim 25:4-5

Keilim 25:4

Regarding a rova and a half-rova (measures of approximately a liter and half a liter, joined to form a single utensil with two receptacles), if the rova contracted ritual impurity, the half-rova is not rendered impure and if the half-rova contracted ritual impurity the rova is not rendered impure. Rabbi Akiva’s students asked: since the half-rova is the outside of the rova, shouldn’t the outside of a utensil whose inside contracts impurity be rendered impure? Rabbi Akiva responded: Are you sure that the rova is the main (and therefore interior) part? Maybe the rova is the outside of the half-rova, and the interior of a utensil certainly isn’t rendered impure if the outside contracts impurity.

Keilim 25:5

If the (interior of the) rova contracts impurity, the rova and its exterior are impure but the half-rova and its exterior remain pure. If the (interior of the) half-rova contracts impurity, the half-rova and its exterior are impure but the rova and its exterior remain pure. Rabbi Meir says that if the exterior of the rova contracts impurity, the exterior of the half-rova remains pure but the Sages say that the exterior cannot be subdivided. When one immerses the utensil, he must immerse it in its entirety.