He mentioned after stating that it is not permissible to raise graves more than what is necessary so as to indicate that it is a grave, “However, with regards to building it very high, similar to what the People of Ignorance (al-Jāhiliyah) would do as a way of exalting or glorifying, then it should be destroyed and removed. This is because doing so is utilizing the beauty (i.e. the manner of adoring the grave as well as the material used) of the dunyā in the first phase of the afterlife. Similarly, doing so resembles those who exalt and worship graves. In consideration of the meanings of these actions and the outward prohibition, then it is fitting to say that this is ḥarām (i.e. prohibited).”
1 Al-Madkhal ilá Tanmiyah al-Aʿmāl bi Taḥsīn an-Niyāt wa at-Tanbīh ʿalá Bʿaḍ al-Bidʿah wa al-ʿAwaʾid allatī Intaḥalat wa Bayān Shanāʿatihi wa Qubhihi, (vol.3, pg.264).