All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The scholars are of the view that it is desirable when placing the books to put the Mus-haf (the Arabic text of the Quran) on top of all of them; this is in regard to books on religious sciences.
However, if what one wants to place over the Mus-haf is not a book on religious sciences, then this is even more disliked, and it can reach the level of forbiddance if this is a way of disrespect to the Mus-haf, like placing shoes over it and the like.
Indeed, the scholars stated that it is forbidden to use the Mus-haf as a pillow, or to weigh with it, or to lean over it, and Allaah Says (what means): {That [is so]. And whoever honors the symbols [i.e. rites] of Allaah — indeed, it is from the piety of hearts.}[Quran 22:32].
Allaah Knows best.