What is the ruling on praying in mosques that have restrooms above them?

Al-Huwaini: Well, we have in EgyptThe Shaykh : Al-Sha'rawi issued a fatwa that it is not permissible to perform the Friday prayer in mosques built under floors?

The Shaykh : Why?
Al-Huwaini: I don't know, I mean, he said something incomprehensible. He said the air of the mosque, and that the mosque might have rooms.

The Shaykh : Up to the seventh heaven.
Al-Huwaini: Yes, that is what it means. Of course, he caused a great deal of confusion because our Salafi brothers do not possess anything but these mosques, meaning that if you took them away from them, they would not be able to pray. So he caused very severe confusion. We need a satisfying answer, if Allah wills, to this question?

The Shaykh : Many of the conditions mentioned regarding some acts of worship, including mosques and the Friday prayer, are actually based on opinion. As we all know, opinion includes what is correct and what is incorrect. If an opinion is issued by a scholar who exercises independent legal reasoning and it is incorrect, he is rewarded—(and peace be upon you, and the mercy of Allah and His blessings)—but an opinion that, after research, is stripped of the compelling evidence from the Book, the Sunnah, or the reports of the righteous Salaf, when such an opinion is stripped of any of these proofs, we direct to it the saying of the Prophet (peace and blessings be upon him): ; so we see no objection to building, for example, a school above a mosque, or building a house above the mosque for the imam, the mu'adhdhin, the servant, or the like. However, I hold the opinion that the toilet must be on the side and not above the mosque; this is in the category of honoring the mosques. As for building a structure on the mosque where no sin is committed, there is no objection to that. Because the claim that what is above the mosque up to the sky of the world or up to the seven heavens is a mosque is a claim devoid of evidence. And the matter is as it was said: "Claims, unless you establish proofs for them, are the claims of claimants." This is what I have regarding this issue, and whoever claims otherwise, we ask them for the argument. Yes.