Mainstream Islamic jurisprudence overwhelmingly considers intentional self-stimulation (istimna) to be impermissible and unlawful, based on Quranic verses enjoining the preservation of chastity and limiting sexual expression strictly to lawful spouses or legal concubines. While scholarly opinions vary slightly regarding the exact severity of the transgression—with some classifying it as a major sin and others viewing it as a minor sin that accumulates if repeated habitually—there is a unanimous consensus among classical and contemporary jurists that Muslims must strive to avoid the practice, seek self-control through fasting, and repent sincerely whenever lapses occur.