Is the exhalation of a ruqyah practitioner into water and honey for a patient to drink included in the prohibition of blowing into drinks, and does it have a basis in Islamic law?

It is legislated for the rāqī (healer performing ruqyah) to blow (with a light spittle) on the patient when reciting the Qur’an. The permissibility of blowing into water has been substantiated by the actions of some of the Salaf, such as A'isha and Imam Ahmad, while the ḥadīth narrated from the Prophet, peace and blessings be upon him, regarding this is weak.

Blowing into water is divided into two categories: 1. Seeking blessings from the spittle of the one blowing: This is forbidden and a form of shirk (polytheism). 2. Blowing with spittle after reciting the Qur’an: This is permissible, proven effective, and beneficial by Allah's permission. Some of the Salaf practiced this.

As for the prohibition of blowing into food, its reason is to avoid defiling it, and this differs from the blowing of the rāqī, which people seek for the blessings of the Qur’an.