Question: What is the ruling on using these book rests which we see in the Haram- the Quran book rests-to place our books on it? Is it an endowment for the Quran alone? Likewise, what is the ruling on using it as a pillow for sleeping on as we many people do?
Answer: “Verily it was placed for the Masaahif and using it for books is like using it for the Mushaf because the benefit is in this and in this. If the origin is using it for the Masaahif and if their is some scarcity, then it is more deserving to use it for the mushaf than for books. If there is no scarcity in using them and a person needs to use it for books and that will not lead to restriction for those who use it for the mushaf, then there is no harm in it. This is because it is a type from this [i.e. it is being used for books]. As for using it as a pillow to lean on behind the back, then this is not what it was put [in the masjid] for”.
[Sharh Sunan Abi Dawood no. 464]
Faisal Ibn Abdul Qaadir Ibn Hassan