Fath al-Rabbani

Benefits: … It is understood from this that it is prohibited to perform istinja (ritual cleansing after relieving oneself) with these things: bones, dung, manure, animal droppings, and coal. Every fleshy bone—by this is meant that Allah Ta’ala causes flesh to grow again upon that bone, which the jinn consume. As for dung and manure, these have been declared, in an absolute sense, as the food of the livestock of the jinn. In Sahih Bukhari, there is a narration from Sayyiduna Abu Hurairah radi Allahu anhu, in which he says: When the Prophet sallallahu alayhi wa sallam finished relieving himself, I asked: What is the reason for not performing istinja with bones and manure? The Prophet sallallahu alayhi wa sallam replied: ((They are from the food of the jinn. Indeed, a delegation of the jinn of Nasibin came to me—and what excellent jinn they were!—and they asked me for provisions. So I supplicated to Allah for them that whenever they pass by a bone or a piece of dung, they will find food upon it.)) … These two things are from the food of the jinn. A delegation of the jinn of Nasibin came to me; they were excellent jinn, and they asked me about provisions, so I supplicated to Allah Ta’ala that whenever they pass by a bone or dung, they find food upon it.

From these narrations, it is understood that bones, dung, and manure are not themselves the food of the jinn and their livestock, but rather, their food is placed upon these things. Allah Ta’ala knows best what the form of that food is and how they benefit from these things. A scholar used to say that since the jinn are subtle (latif) beings, they obtain nourishment from these things by smelling them. And Allah knows best.