What is the ruling on flies defecating and sleeping on copies of the Qur’an and religious da’wah books and papers hung on walls? And is one who leaves them in such a state like one who leaves a copy of the Qur’an in filth?

The fly specks on the Mus'haf are not considered placing the Mus'haf in filth because it is a forgiven impurity. Scholars differed on the permissibility of placing the Mus'haf on a forgiven impurity; some permitted it, while others prohibited it. An-Nawawi permitted it, while others viewed it as forbidden. Whoever removes the specks from the Mus'haf has done well, and whoever does not, there is no blame upon him. As for religious books and da'wah papers, throwing them in filth does not necessitate only disciplinary action, and it is permissible to place them on something with fly specks, by أولى (priority).