Mishnah Oholot 16

¹All movable things convey uncleanness when they are of the thickness of an ox-goad. Rabbi Tarfon said: May I [see the] demise of my sons if this is [not] a demised halakhah which someone heard and misunderstood. For a farmer was passing by and over his shoulder was an ox-goad, and one end overshadowed a grave. He was declared unclean on account of vessels that were overshadowing a corpse. Rabbi Akiva said: I can fix [the halakhah] so that the words of the sages can exist [as they are]: All movable things convey uncleanness to come upon a person carrying them, when they are of the thickness of an ox-goad; Upon themselves when they are of whatever thickness; And upon other men or vessels [which they overshadow] when they are one handbreadth wide. ²How so? A spindle stuck into the wall, with [a portion of corpse] of half an olive-size above it and [a portion of corpse] of half an olive-size below it. Even though one [portion] is not directly [above] the other, [the spindle] becomes unclean. Hence it is found that [a movable object] conveys uncleanness to come upon itself whatever its thickness. A pot seller passes by a grave with a yoke over his shoulder, one end of which overshadows a grave, vessels on the other side remain clean. If the yoke is one handbreadth wide, they become unclean. Mounds which are near to a city or to a road, whether they are new or old, are unclean. [As for those that are] far away, new ones are clean but old ones are unclean. What counts as near? Fifty cubits. And old? Sixty years old, the words of Rabbi Meir. R. Judah says: Near means there is none nearer than it, and old means that no one remembers [when it was made]. ³If one finds a corpse unexpectedly lying in its natural position, he may remove it along with the [blood-] saturated earth around it. If he finds two, he may remove them along with the [blood-] saturated earth around it. If he finds three, if there is a space of from four to eight cubits between the first and the last, that is, the space of a bier and its bearers, then it must be accounted a graveyard. He must search [the ground] for twenty cubits from that point. If he found [another corpse] at the end of those twenty cubits, he must search for a further twenty cubits from that place, since there are already grounds for belief [that this is a graveyard], in spite of the fact that if he had found this [lone grave] in the first case, he could have removed it with the [blood-] saturated earth around it. ⁴One who searches, must search over a square cubit and then leave a cubit, [digging down] until he reaches rock or virgin soil. [A priest] carrying out earth from a place of uncleanness may eat his terumah mixed with hullin. But one who is clearing away a heap of stones, may not eat his terumah mixed with hullin. ⁵If he was searching and came to a river bed, or a pool or a public road, he may end [his search]. A field in which men have been slain, he may gather the bones one by one, and all [the area] may be accounted clean. One who removes a grave from his field, he may gather the bones one by one, and all [the area] may be accounted clean. A pit into which they throw fetuses or people that had been slain, he may gather the bones one by one, and all [the area] may be accounted clean. Rabbi Shimon says: if it had been prepared as a grave in the first place, there is [blood-] saturated earth.