What is the legitimacy of torture in Islam, and did it exist during the time of the Messenger and the Rightly Guided Caliphs to protect state security, and to what extent was this torture practiced if it existed, and did the Umayyad and Abbasid Caliphs practice it?

Allah Almighty has forbidden assaulting a Muslim in any form and has prescribed a legal punishment for it, in accordance with His saying: "And We ordained for them therein a life for a life, an eye for an eye, a nose for a nose, an ear for an ear, a tooth for a tooth, and for wounds is legal retribution." The Prophet Muhammad, peace and blessings be upon him, emphasized the sanctity of a Muslim's blood, property, and honor.

Torturing prisoners and accused individuals is fundamentally forbidden. However, some scholars have made an exception for an accused person known for their immorality, permitting slight torture for them to confess to the crime they are accused of. They agreed on the permissibility of torturing someone known to possess the truth but who denies it.

Shaykh al-Islam Ibn Taymiyyah divided claims into: claims of accusation (like felonies) and claims of non-accusation (like contracts). In claims of accusation, he divided the accused into three categories: 1. The innocent: It is unanimously agreed that they should not be punished. 2. The unknown: They are detained until their situation becomes clear. 3. The known for immorality: It is permissible to imprison and beat them according to some scholars, while others say they should be imprisoned but not beaten.

As for the punishment of one who is known to possess the truth but denies it, it is agreed upon by scholars, and they are punished with beating and imprisonment until they render the right.