A wailing field may not be planted with either trees or grains, and its soil is tahor. [Furthermore,] one may make ovens for holy items [from its clay]. Beis Shammai and Beis Hillel agree that we check [for bone fragments] for one making the pesach offering, but we do not check for [one who eats] terumah. And as far as a nazir is concerned, Beis Shammai say: We check it, and Beis Hillel say: We do not check it. How does he check? He brings earth that can be moved and places it inside a sifter with very thin holes and crumbles (any clods) — if there was a bone the size of a barleycorn was found, [the person] becomes tamei.