Is it permissible to write Ayatul-Kursi or a Surah from the Qur’an, then place it in water and drink it? And are there specific Surahs or verses for this purpose? And can this be done with supplications (du’a) that are not from the Qur’an? And are there specific supplications mentioned in the Sunnah that are dissolved in water in this manner?

Scholars have differed on the ruling of writing Qur'anic verses on paper or a tablet, then washing it and drinking the water for healing. Some considered it an innovation (bid'ah), while others among the Salaf permitted it. This has been narrated from Mujahid, Abu Qilabah, Al-Hasan al-Basri, and Al-Awza'i, and Imam Ahmad explicitly stated its permissibility.

There is no harm in doing so, provided that the Qur'an is written with pure ink on a pure surface. One must be careful not to write it with blood, as it is impure. It is preferable to drink it rather than to wash with it. Washing with it is disliked so that the water of the Qur'an does not flow into impure places. What is written must be verses from the Qur'an, or remembrance of Allah, or His supplication with understandable words. It is not permissible to write talismans or anything whose meaning is not understood, or that contains polytheistic incantations, due to the Prophet's (peace be upon him) saying: "Present your ruqyahs to me. There is no harm in ruqyahs as long as they do not contain shirk (polytheism)." No authentic evidence has been reported specifying particular surahs or verses to be written, except what was narrated from Ibn Abbas concerning facilitating childbirth.