Shaykhul-Islam Ibn Taymīyyah (may Allāh have mercy upon him):
If the Jinn is from the Afārīt and he (the one performing the Ruqyaa) is weak, they can harm him. Therefore, the likes of this person is to protect himself with the recitation of that which gives refuge and protection like Āyah al-Kursī, the Mu’auwwidhāt (Sūrah al-Falaq and Sūrah an-Nās), the making of the prayer, supplication and the likes of that from that which strengthens the faith. He is also to keep away from the acts of sins which (cause the enemies) to gain authority over him. For indeed, he is one who is striving on the path of Allah and this is from the greatest of the categories of Jihād (striving for the sake of Allah). Therefore, let him beware that he aids the enemy against himself by way of the committing of sins. If the matter is above his ability, then Allāh doesn’t burden a soul except with that which it has the ability to do. So let him not subject himself to the calamities which he doesn’t have the ability to withstand.
Source: Majmū’ al-Fatāwā, v. 19, pg. 53
Translated by Abu Yusuf Khaleefah
12th of Rabī’ al-Thāni, 1437 (01-23-2016)
Masjid Nur Allah, Queens, NYC