Is it true that Ali ibn Abi Talib used to recline on graves and sit upon them? And to whom is this narration attributed, and in which book is it found?

Scholars have differed concerning the ruling on sitting on graves. The majority of scholars have deemed it forbidden, citing prophetic traditions that prohibit it, among them: "For one of you to sit on a burning ember that burns his clothes and reaches his skin is better for him than to sit on a grave," and "Do not sit on graves and do not pray towards them."

However, the Malikis, some Hanafis, Zayd ibn Thabit, and others, permitted it. They interpreted the aforementioned hadiths as referring to sitting on a grave to relieve oneself, citing the action of Ali ibn Abi Talib, may Allah be pleased with him, who used to recline on graves and lie down on them, and the actions of Yazid ibn Thabit and Ibn Umar, may Allah be pleased with them, who used to sit on graves. Malik said that the prohibition against sitting on graves, in our view, is for answering the call of nature. And it was said that this was disliked for those who had defiled it.

Zayd ibn Thabit narrated that the Messenger of Allah, peace and blessings be upon him, forbade sitting on graves for urination or defecation. Al-Shawkani indicated that the authentic hadiths prohibit sitting on graves, and that there is no argument against what is established from the Prophet, peace and blessings be upon him.