Ruqyah (رقى) is when one performs lawful supplications to ask for Allāh (سبحانه و تعالى)'s assistance, and sometimes blowing spittle and reciting the Qurʾān. However, there are incantations, when one seeks assistance for other than Allāh (سبحانه و تعالى), resulting in Shīrk (polytheism).
Allāh (سبحانه و تعالى) says in the Qurʾān:
A few proofs of the permissibility of Ruqyah is also found in several Ḥādīth, one of them which I will include here:
The Prophet (ﷺ) said:
This ḥādīth proves the permissibility of Ruqyah, except if they are made seeking Allāh's assistance and not associating any partners with Him. So this basically means it must be done islāmically without Shīrk. It also must be done for someone of knowledge, so that the Ruqyah is free from any oppositions to the religion.
And the Prophet (ﷺ) also encouraged Ruqyah:
May Allah bless you, and shukran.
1. Qurʾān 75:27
2. Authentic ḥādīth in Ṣaḥīḥ Muslim
3. Reported by Muslim