The Prophet (may Allah's peace and blessings be upon him) was keen to direct the Muslims to what demonstrates honor among themselves, both in life and after death. So, in this Hadīth, he prohibited sitting on the graves and was vehement in this prohibition. He (may Allah's peace and blessings be upon him) informed and warned that if a person sits on a piece of inflaming fire and this live coal burns his clothes and reaches his skin, which involves tremendous harm and severe pain, this burning of his clothing and skin is better and easier for him than sitting on a grave. This is a stern warning and emphatic prohibition from sitting on graves. He forbade sitting on graves because this constitutes belittlement of the rights of fellow Muslims, even if they are dead. The usual practice regarding the graves is only to visit them and supplicate there while standing, as the Messenger of Allah (may Allah's peace and blessings be upon him) used to do when he headed to the Baqī' cemetery. He would say: "Assalāmu ‘alaykum ahl ad-diyār min al-mu’minīn wa al-muslimīn, wa inna in shā’ Allah la lāhiqūn; as’al Allah lana wa lakam al-‘āfiyah" (Peace be upon the dwellers of this place among the believers and Muslims. Indeed, we will join you, Allah Willing. I ask Allah for safety for you and us). Narrated by Muslim..