Mishnayos Oholos Perek 17 Mishnah 1

יז

החורש. בית הפרס – a place where the defilement is separated and flattened/straightened there. But my Rabbis explained that [the word] פרס is "דבר פרוס ושבור" (see also the Bartenura commentary to Tractate Niddah, Chapter 7, Mishnah 5 where the same phrase appears) something that is broken and injured, that the bones of the corpse were broken/divided there. And from the mouth of others I heard that as a result that the feet of human beings are prevented from walking there because of the defilement.

מלא מענה (a furrow’s length) – of a plough. From the place of he grave that he began to plow until one-hundred cubits along the length of the field by one-hundred [cubits] in width, we are concerned lest the plough carries from him a [piece of human] bone the size of a barleycorn. But if he would continue ploughing outside of the one-hundred cubits, from one-hundred cubits and outward, it is ritually pure, for the plough does not carry bones of a grave other than up until one-hundred cubits.

בית ארבעה סאין (a space of four Se’ah) – one-hundred cubits in length by one-hundred cubits in width is the place of seeding four Se’ah. For the courtyard of the Tabernacle that was one-hundred by fifty is Bet Se’atayim, as we state in [Tractate] Eruvin [23b], it is found that one-hundred cubits by one-hundred cubits is a Bet Arbah Se’ah.

רבי יוסי אומר בית חמש – but the Halakha is not according to Rabbi Yossi.

ובמורד (and in descent) - meaning to say, this measure that we stated to the first Tanna/teacher [of the Mishnah] and to Rabbi Yossi, to him as he holds and to the other (i.e., Rabbi Yossi) as he holds, these words [refer to] when the plough carries in descent, that it [looks like he] is rolling it from afar, and the same law applies when the land is on a plain level. But in an ascent, when he plows and ascends, according to the words of the first Tanna/teacher, he gives a quarter of a Kab of vetches on the knee-shaped pole of the plough- as far as the knee of the plough enters the soil, which is a bent wooden cavity made like a knee that the plough is affixed to, and it makes in its rim/bottom of the vessel a small incision like the measure that went out from it one globule/stone or kernel of a stone fruit, nut from the globules of the vetches, and it brings the plough and the globules fall off bit by bit, and in a place where the vetches have run out, not much falls from them together other than three globules each one by the side of the other and there was completed the Bet HaPras (i.e., the place declared - unclean on account of crushed bones carried over it from a ploughed grave).