민수기 19:15 미슈나 참조: Mishnah Eduyot, Mishnah Parah & Mishnah Kelim

A vessel of earthenware can protect everything [in it from contracting impurity], according to Beth Hillel. But Beth Shammai says: “It protects only food and liquids and [other] vessels of earthenware.” Beth Hillel said to them: “Why?” Beth Shammai said to them: “Because it is [itself] impure with respect to an ignoramus, and no impure vessel can screen [against impurity].” Beth Hillel said to them: “And did you not pronounce pure the food and liquids inside it?” Beth Shammai said to them: “When we pronounced pure the food and liquids inside it, we pronounced them pure for him [the ignoramus] only, but when you pronounced the vessel pure you pronounced it pure for yourself and for him.” Then Beth Hillel changed their mind and taught according to the opinion of Beth Shammai.

They can make the mixture in all kinds of vessels, even in vessels made of cattle dung, of stone or of earth. The mixture may also be prepared in a boat. It may not be prepared in the walls of vessels, or in the sides of a large jug, or in the stopper of a jar, or in one's cupped hands, for one does not fill up, or mix in, or sprinkle the hatat with anything but a vessel. Only on a vessel does tightly fitting cover afford protection, for only in vessels is protection afforded against uncleanness within an earthen vessel.

If there was netting placed over the mouth of an oven, forming a tightly fitting lid, and a split appeared between the oven and the colander, the minimum size [to allow impurity to enter] is that of the circumference of the tip of an ox goad that cannot actually enter it. Rabbi Judah says: it must be one into which the tip can actually enter. If a split appeared in the netting, the minimum size is the circumference of the tip of an ox goad that can enter it. Rabbi Judah says: even if it cannot enter. If the split was curved it must not be regarded as straight, and still the minimum size must be the circumference of the tip of an ox goad that can actually enter.