Quranic inscriptions/calligraphy on the walls

His Eminence Sheikh Ibn Al-Uthaymeen rahimahullah was asked: What is the ruling on writing Quranic Ayaat and Prophetic hadiths on the walls of the masaajid? He replied: This disturbs people. As for writing Quranic Ayaat on walls, whether in the masjid or elsewhere, then this is an innovation; the Companions never used to engrave Quranic Ayaat on their walls. Moreover, inscribing Quranic Ayaat on walls is a form belittlement of the Speech of Allah, and that is why we find some of them writing Quranic Ayaat in the form of palaces, minarets, masaajid, and the like; they structure the writing in the form of a palace, and no doubt this is messing with Book of Allah. Even if it was written in an understandable/clear Arabic script, that is still not from the guidance of the Salaf. What is the benefit of writing it on the walls? Some people say: It serves as a reminder for people, so we say: reminder is through speech, not by writing the Ayaat. Sometimes they write on the wall: {وَلا يَغْتَبْ بَعْضُكُمْ بَعْضاً} “And do not backbite one another.” [Surah Al-Hujurat 12] And you find those sitting under this Ayah backbiting people, so he is like one who mocks the Ayaat of Allah. So, writing Quranic Ayaat in the masjid and on the walls of the homes is an innovation that was not known at the time of the Salaf... [Liqaa' Al-Baab Al-Maftooh 197, Question 8]