I have been told that there never was one. Yet, R' Yonasan said that he saw one and he sat on his grave.
1) Doesn't this mean there definitely was one?
2) How could R' Yonasan, a Kohen, sit on a grave?
3) Is it proper to sit on a grave?
Re these answers, question 2 says to see Margaliyos HaYam and Einayim LaMishpat and question 3 says to see Pischei Teshuvah to Yoreh Deah 364:2. I don't read Hebrew so I need your assistance.
Barry Epstein, Dallas, USA
1) There is a Tana who argues, so it cannot be definite. As for the testimony of Rebbi Yonasan, Rabeinu Bachye (Devarim 21:21) writes that it may not have been a true Ben Sorer for which the Torah prescribes Sekilah; rather, a disobedient child (such as Abshalom) who *ought to have been* a Ben Sorer u'Morer, if he would fit the other Halachic requirements.
2) Rabeinu Bachye's Girsa is "Rebbi Yochanan." According to our Girsa, he may have sat near it but not on it.
3) See above 2. Below please find what the Kollel wrote on the subject (Insights to Sanhedrin 48:1).
Best wishes,
M. Kornfeld
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Sanhedrin 48
1) HALACHAH: SITTING ON A GRAVESTONE
OPINIONS: The Gemara says that if a person builds a gravestone over a grave, the stone becomes Asur b'Hana'ah. Can we learn from here that it is prohibited to sit or lean on a gravestone in a graveyard?
(a) The TUR (beginning of YD 364) cites RABEINU YESHAYAH who, based on our Gemara, prohibits using a gravestone. The BEIS YOSEF cites the HAGAHOS ASHIRI in the name of the OR ZARU'A (Moed Katan 3:79) who writes that some prohibit sitting and leaning on a gravestone for this reason.
(b) However, the Tur cites his father, the ROSH, who permits using gravestones today, since they are not part of the grave but merely a marker for the grave. Apparently, in the times of the Gemara the gravestones were part of the grave itself, and not merely markers above the grave.
This is also the opinion of the RASHBA (in a Teshuvah cited by the BEDEK HA'BAYIS) and the OR ZARU'A (Hilchos Aveilus 423), who write that today's gravestones are simply erected to give honor to the dead, but they are not Asur b'Hana'ah.
The Rashba there and RABEINU YERUCHAM cited by the BACH give another reason to permit sitting on gravestones. They write that it was customary for people to sit on gravestones. Consequently, when the gravestone was erected, it was considered as though it was done with an explicit condition permitting people to sit or lean on it.
HALACHAH: Both opinions are cited by the REMA (YD 364:1). Accordingly, in a place where it is not the accepted practice to sit on gravestones, there may be reason to be stringent (since the second reason for leniency does not apply). In addition, there is another reason to prohibit sitting on a gravestone. The Gemara in Megilah (29a) prohibits letting animals graze in a graveyard or acting lightheadedly in a graveyard. The MORDECHAI in Megilah there asks why should it be prohibited to graze animals there; the Isur Hana'ah only prohibits deriving benefit from the grave itself, and not from the whole graveyard. Moreover, even the grave itself becomes Asur only when one builds a structure in which he places the Mes. The dirt of the grave itself does not become Asur. The Mordechai answers that the Isur in the Gemara in Moed Katan is not because of the Isur Hana'ah, but because of the disgrace to the dead involved in grazing animals there.
The Acharonim (YAD ELIYAHU, cited by PISCHEI TESHUVAH YD 364:2) write that the concern for disgrace to the dead also prohibits a person from sitting or standing over a gravestone. (Leaning on a gravestone might not be considered a disgrace.)