What is the meaning of "the dowry of a harlot is impure" mentioned in the Hadith: "The price of a dog is impure, the dowry of a harlot is impure, and the earning of a cupper is impure"? And is it permissible for a Ruqyah practitioner to demand large sums of money?

The dowry of a prostitute (mahr al-baghi) mentioned in the Hadith refers to the payment an immoral woman receives for committing adultery, and it is metaphorically called a dowry. As for the one who performs ruqyah (exorcism/healing with Quranic verses) according to Islamic law, there is no harm in him taking a fee for his ruqyah, provided that it is not unfair to the patient, in order to align with the moderation of Islam.