Muhammad used torture. Here are a couple of documented quotes from http://www.thereligionofpeace.com/Quran/029-torture.htm:
Muslim (16:4131) – They were caught and brought to him (the Holy Prophet). He commanded about them, and (thus) their hands and feet were cut off and their eyes were gouged and then they were thrown in the sun, until they died. Muhammad had two killers put to death, not in the way of “an eye-for-an-eye,” but in a more agonizing manner.
Torture is also allowed when putting people to death. Rather than prescribing quick execution of captives, there were times in which Muhammad ordered his men to make a victim’s death as slow and agonizing as possible. In one case, Muhammad’s men literally pulled apart the body of an elderly woman named Umm Qirfa by tying her limbs to camels then sent in opposite directions (Ibn Ishaq 980).