Sitting on Tombstones
The Shulchan Aruch records a machlokes (a debate) among poskim whether one is allowed to sit—or even lean—on a matzeivah (tombstone), since we may not benefit from anything that is done for the sake of a meis (a deceased person). Those poskim who permit it are of the opinion that the matzeivah is not something that benefits the meis, rather it is erected solely as a sign of respect for the deceased, and therefore we may benefit from it. Many poskim suggest that this prohibition applies only to horizontal tombstones that lie over the grave, since they also serve to protect the body, but the vertical ones that stand at the head of the grave are clearly erected as a sign of respect—and it is permissible to sit and lean on them. Nevertheless, the prevailing custom is not to sit on the vertical ones either, due to the opinion that the prohibition applies to both types of tombstones. It is also possible that this custom originated out of sensitivity for the deceased, and is not based on halachah. #303