What is the ruling on masturbation (self-pleasure) by hand or by fantasizing?

Masturbation by hand is forbidden (haram) and has many harms. As for masturbation through thinking about forbidden things, it is also forbidden (haram) and is considered a form of zina (illicit sexual intercourse), as stated in the Hadith: "The heart yearns and wishes, and the private parts either confirm that or deny it." And if the thinking is about a wife or a fleeting thought, it is a futile act that serves no purpose but to arouse instincts. A believer must occupy the blessing of thought with what strengthens their faith, and contemplate Allah's signs and what benefits them in matters of their religion and their worldly life.