Ohalos, Chapter 16, Mishnah 3. A short introduction will set the stage for everything the Mishnah says here.
Three times a year Klal Yisroel came up to Yerushalayim to be oleh regel. Ahead of the crowds, inspection teams went out along the roads, and their assignment was to verify that the routes were free of tumah. Think about who would soon be walking there: kohanim, families eating terumah, Yidden particular about taharah. Picture an army detachment sent forward to clear a road of mines before the soldiers march; in the era of the Beis Hamikdash the hazard being searched for was tumah rather than explosives.
Suppose one of these teams came across a kever on the route. Their first question was whether the niftar could be relocated. If the grave belonged to an established beis hachaim, a burial ground meant to stand until techiyas hameisim, the body stays where it is; whoever lies there has already taken possession of that spot. In that case the team's option was to place clear markers around the area so that the olei regel would notice it and detour around it. So the Meiri explains in Meseches Nazir.
Our Mishnah supplies the criteria for that very determination: does a discovered grave belong to a cemetery, where nothing may be done beyond marking the boundaries, or was the burial only a stopgap, with the intent that the body be moved afterwards, in which case relocating it is permitted?
One Body Uncovered
The Mishnah begins: "Hamoitzei meis batchilah," one who finds a corpse at the start. Someone is digging and unexpectedly strikes a grave.
The Bartenura, based on the Gemara in Meseches Nazir, notes how carefully the word "hamoitzei" is chosen. It conveys a find that came as a complete surprise; the digger had no advance information that anyone was buried there. Where he did know beforehand that a grave lay at that spot, he may not shift it, even when it stands alone, because the working presumption is that whoever is buried was buried to stay. Precisely because the grave turned up out of nowhere in the middle of digging, we are able to entertain that the burial there was only provisional, and on that basis moving it is permitted.
A second nuance lies in the wording. The Mishnah's term "meis" tells us we are dealing with one who died naturally, not with a victim of killing.
So the man is digging and suddenly stops short: a kever. He now has to inspect what he has hit. Should the body lie "mushkav kedarko," arranged the way Yidden lay a niftar to rest, limbs extended, hands over the heart, then "noitlo ve'es tfusaso": he removes him with his tfusah and buries him in a different place. Tfusah refers to a quantity of earth taken from below the body.
The logic: only one body surfaced here, and nothing establishes that he was placed here for good, so we assume no fixed cemetery was ever intended. Most likely he was put here on the understanding that he would later be transferred, and therefore moving him now is muttar.
Why Soil From Below Accompanies the Body
What is the source for bringing along earth from underneath the body? Yaakov Avinu. When he charged that his remains be brought up out of Mitzrayim, his instruction was that he be carried "miMitzrayim" and laid in the burial place of his fathers. Why did he have to specify the place he was being carried from? That was self-evident. Chazal therefore derive that he was requesting that a portion of the soil of Mitzrayim travel with him to Eretz Yisroel.
Some hold that on account of this hint in the posuk the practice carries the standing of a Torah source. Others give a practical reason: matter from the body may have soaked into the ground below it, and we want that soil to go along too.
Two Bodies
The Mishnah continues: "Matza shnayim," should he find two. The possibility of a provisional burial is still open, and so "noitlon ve'es tfusasan," he removes both together with the earth under them.
How deep does the digging go? Down to "karka besulah," untouched virgin ground, and three etzba'os, fingerbreadths, into it.
Three Bodies
"Matza sheloshah," should he find three lying in the usual position, the entire picture shifts. He must now look at how they are laid out and measure grave to grave. "Im yesh bein zeh lazeh me'arba amos ve'ad shemoineh": if the interval from the first to the third is at least four amos and does not exceed eight, that is exactly the spacing of burials in a cave, and "harei zu shechunas kevaros," a burial cluster. Those laid to rest here were meant to stay until techiyas hameisim; the place is theirs, and it is assur to relocate them.
A point of precision: even one lone body, where clear simanim show that the burial was lesheim kevurah rather than a temporary measure, may not be moved. Only when no such indication exists are we free to suppose, with one or two graves, that the interment was meant to be undone later. Once three are found in these proportions, we conclude definitively that a functioning beis hachaim is before us, and moving anyone is not an option.
From where do we get these figures, a minimum of four amos and a maximum of eight between the first grave and the third? We will arrive at that be'ezras Hashem; first let us follow the Mishnah to its end.
Twenty Amos in Every Direction
Once three graves have shown that this is a beis hachaim, additional graves are likely close by. Anyone who wants to pronounce the surroundings clean has to check, and the Mishnah spells out how: "boideik mimenu ulehallan esrim amah," he inspects outward from that grave for twenty amos in each direction, looking for more bodies.
"Matza echad besof esrim amah," if even a single body appears at the twenty amah mark, that grave is presumed to belong to the same burial complex, and the checking is not over: "boideik mimenu ulehallan esrim amah," from this body too he inspects a further twenty amos all around. Why? "She'raglayim ladavar," there is real footing for the concern. Something concrete stands in front of us pointing to further burials in this ground, or at minimum to a serious probability of them.
The Mishnah then highlights the contrast: "she'ilu mitechilah matza," had this solitary body been the first thing he came upon, before the three came to light, "notlo ve'es tfusaso," he could have taken it away with the soil beneath it, with no worry whatsoever about a fixed cemetery. But Hashem arranged that the lone grave was not what met him first. The three appeared first, and now every further body he uncovers imposes another twenty amos of searching all around, and each one is treated as belonging to the permanent cemetery and stays where it is. Had the single grave come to light before them, off it would have gone. Since the three surfaced first, the search keeps widening in twenty amah stages, even though the graves he continues to find are isolated ones.
The Mishnah in Review
Let us put the halachos in order. Someone who comes upon a body and can tell that this is a kever Yisroel lifts it out with a measure of the earth under it and buries it elsewhere, since a single burial in one spot carries no presumption of a lasting cemetery; he may therefore be moved and the road opened for those coming to be oleh regel. Two bodies: the same ruling, with the excavation reaching untouched soil and continuing three fingerbreadths into it. Three bodies: measurements are required. If the intervals match the pattern of a burial cave, this must be a beis hachaim; not only do those three remain in place, but twenty amos in every direction require inspection. Find even one body there, and twenty amos are inspected outward from that grave as well, and so on for as long as bodies keep appearing. All of it is presumed part of a cemetery meant to last until techiyas hameisim.
A Story of Daas Torah
Since our subject is how a Yid is laid to rest, here is the familiar episode involving Reb Moshe. A moser in his town served the Soviet regime, and the anguish he caused Yidden defies telling: households ruined, people deported to Siberia. He was a rasha through and through. Shortly before his death he left instructions with the Chevra Kadisha that he be buried inverted, head down and feet up.
The Chevra Kadisha saw nothing wrong with honoring the request. To them it was fitting: a man who caused such misery should go into the ground the way an animal would, and if he was asking for it himself, all the better. They brought the question to Reb Moshe, who was the rav of the town. His answer was that such a thing is out of the question; halachah does not allow a person to be buried that way. They pressed: the man was a moser, a rasha. He repeated that halachah forbids burying a person like that. And so the man was buried in the ordinary, proper manner that halachah requires.
No sooner was the burial over than Soviet police showed up and opened the grave. The man's malice had been planned to the last detail: he had left the instruction with the Chevra Kadisha and had also told the police in advance to exhume him. They would then have found that Yidden had degraded the body of a government agent, and that would have been the excuse for arrests without number. But the rav had ruled that a Yid is buried as halachah dictates, and there is no way to count how many lives that psak of Daas Torah rescued.
Where the Measurements Come From
Now to the arithmetic. What produces the range that runs from four amos at the low end to eight at the high end between the first grave and the third? Whoever wishes may move ahead to the next Mishnah, since the content of ours is already clear; for those who want the calculation, here it is.
Think back to the sugya in Meseches Bava Basra and the chatzar hakevaros, the courtyard of the graves. Burial in those times was in caves: there was a courtyard, and from it one entered the caves. The cave itself had an open floor area of modest size, six amos deep and four amos across. Walking straight in you had six amos before the back wall; going from one side to the other you had four.
The walls of the cave were carved out with kuchim, niches tunneled straight into the rock, each one an amah in width, and a body was laid inside each niche.
Now visualize it. I step into the me'arah. Three kuchim open on my right, three on my left, and two face me at the back. How do the numbers work? The cave runs six amos in length and four in width, every niche measures an amah across, and a full amah of rock has to separate each niche from the next.
Take the wall on my left as I enter: half an amah of rock at the corner, a niche of an amah, an amah of rock, a second niche of an amah, another amah of rock, a third niche of an amah, and half an amah of rock at the far corner. The sum: three niches equal three amos, the two spans between them equal two amos, which brings us to five, and the two half amos at the corners round it out to six. Five plus two halves is six. The wall on the right is built exactly the same way.
That yields the lower figure. Measure along one wall from the first grave to the third: an amah of niche, an amah of rock, an amah of niche, an amah of rock, and the third niche starts there. So from where the first grave begins to where the third begins is four amos, two niches plus the two separations between them.
And the upper figure of eight? Picture the cave once more, three niches left and three right. Run a diagonal line from the first niche on one side across the cave to the far edge of the third niche opposite. That line works out to something close to eight amos, in truth a little under, but roughly eight.
Here is why it matters. A man with a shovel in the ground has no sense of direction. He turns up one body, then a second, then a third, without knowing which way his digging is running. He may be following a single wall, or he may be cutting across the cave on a diagonal. On the diagonal, the distance from the first body on one wall to the third on the opposite wall comes to roughly eight amos. The figures actually produce a trifle less, and the Rambam accounts for this by saying that Chazal took the stringent route and rounded the number upward. Along one wall, then, the distance from the start of the first niche to the start of the third is four amos at the least; on the diagonal, from the first on the left to the third on the right, eight.
That is the cheshbon underlying the Mishnah. When three bodies come to light and the gap between the first and the third is neither under four amos nor over eight, he has to assume that he has opened a burial cave, an ordinary beis hachaim, and disturbing the menuchah of those lying there is forbidden to him. Their neshamos have their place in Gan Eden; shifting their bodies here below unsettles them and causes them difficulty. Doing so runs against halachah, absent a compelling need. There were situations, as occurred at times in Europe, where a beis hakevaros itself faced the threat of being excavated and built over chas veshalom. Under such conditions a beis din could rule, al pi halachah, that the graves be transferred, and precisely out of kavod for those buried in them.