Is it permissible to use Indian costus as incense in Ruqyah Shar'iyyah?

The fundamental principle regarding fumigating with permissible substances is permissibility. However, treating illnesses with incense is a practice of charlatans. It is better to do without it and instead use the prescribed supplications and legitimate ruqyah. Ruqyah with the Qur’an, supplications (du'a), and dhikr (remembrance of Allah) is an effective remedy. Aishah, may Allah be pleased with her, narrated that the Prophet, peace and blessings be upon him, "entered upon her while a woman was treating her or performing ruqyah on her. He said: 'Treat her with the Book of Allah.'"

It is well-known from the Salaf regarding ruqyah with the Qur’an that it is recited over the sick person. It is also permissible to recite the Qur’an over water, and then the sick person drinks from it, or to write it on a tablet or paper, wash it off, and drink the water. Ibn al-Qayyim transmitted his personal experiences of seeking healing by reciting Surat al-Fatiha over the painful area or over Zamzam water and drinking it. Similarly, Ibn Muflih narrated from Salih, the son of Imam Ahmad, that his father used to recite over water and instruct him to drink it and wash himself with it.