What is the ruling on thinking about sorcery and how does one repent from it?

There is no sin in thinking about a transgression as long as it does not reach the point of firm intention, for the Prophet, peace and blessings be upon him, said: "Indeed, Allah has forgiven my Ummah for whatever whispers (waswasa) or thoughts occur in their hearts, as long as they do not act upon it or speak of it." However, a person sins if they firmly intend to commit the act.

Repentance involves regretting what has passed, abandoning the firm intention, and resolving not to return to the transgression in the future.