Qur’an 5:33 “The punishment for those who wage war against Allah and His Prophet and make mischief in the land, is to murder them, crucify them, or cut off a hand and foot on opposite sides...their doom is dreadful. They will not escape the fire, suffering constantly.”
Tabari VIII:122/Ishaq:515 “The Prophet gave orders concerning Kinanah to Zubayr, saying, ‘Torture him until you root out and extract what he has. So Zubayr kindled a fire on Kinanah’s chest, twirling it with his firestick until Kinanah was near death. Then the Messenger gave him to Maslamah, who beheaded him.”
Qur’an 9:5 “When the sacred forbidden months for fighting are past, fight and kill the disbelievers wherever you find them, take them captive, torture them, and lie in wait and ambush them using every stratagem of war.”
Ishaq:595 “The Apostle said, ‘Get him away from me and cut off his tongue.”” Qur’an 8:12 “Your Lord inspired the angels with the message: ‘I will terrorize the unbelievers. Therefore smite them on their necks and every joint and incapacitate them. Strike off their heads and cut off each of their fingers and toes.”
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They terrorize in order to make their enemies surrender. A terrified enemy will give up fighting, thus the Muslims save their own lives. From the yellow bellied coward school of military tactics