Bava Batra 102A

מצא שלשה ⁠– אם יש ביניהן מארבע עד שמונה, הרי זו שכונת קברות, ובודק ממנו ולהלן עשרים אמה. מצא אחד בסוף עשרים אמה ⁠– בודק ממנו ולהלן עשרים אמה, שרגלים לדבר. שאילו מתחלה מצאו ⁠– נוטלו ואת תפוסתו.

If he found 3 corpses lying parallel to each other, then if there is between them, i.e., the outer two corpses, a distance of 4 to 8 cubits, then this is presumed to be a graveyard and the corpses may not be removed, and he must examine from that spot outward 20 cubits to discover whether there are other corpses buried there. If he finds even one corpse up to the distance of 20 cubits, he must continue to examine from the place he finds that corpse outward another 20 cubits. He continues to search for additional corpses, even if only one corpse was found within the 20 cubits, as there is a basis for anticipating the matter; it is probable that he has stumbled upon an ancient cemetery. He is not permitted to relocate the corpses, despite that fact that if he had found the single corpse by itself at first, without being aware of the gravesite, he would have been permitted to remove it and its surrounding earth.

אמר מר: מארבע ועד שמונה. מני? אי רבנן ⁠– הא אמרי: ארבע אמות על שש! אי רבי שמעון ⁠– הא אמר: שש על שמונה!

The Talmud analyzes that Mishnah. The Master said: If there is between them a distance of 4 to 8 cubits, then it is presumed to be a graveyard. The reason is that corpses buried in this manner are indicative of the standard layout of a burial chamber. The fact that this is said only when the distance between the corpses is between 12 cubits assumes that the size of a burial chamber is 4 cubits by 8 cubits. Based on this, the Talmud asks: Whose opinion is this? If it is the opinion of the Rabbis in the Mishnah above (100b), didn’t they say that the size of a burial chamber is 4 cubits by 6 cubits? If it is the opinion of R' Shimon, didn’t he say that a burial cave is 6 cubits by 8 cubits?