Yahya related to me from Malik from a man of Kufa that Umar ibnal-Khattab wrote to a lieutenant of an army which he had sent out, "Ihave heard that it is the habit of some of your men to chase anunbeliever till he takes refuge in a high place. Then one man tellshim in Persian not to be afraid, and when he comes up to him, he killshim. By He in whose hand my self is, if I knew someone who had donethat, I would strike off his head."Yahya said, I heard Maliksay, "This tradition is not unanimously agreed upon, so one does notact on it."Malik when asked whether safe conduct promised bygesture had the same status as that promised by speech, said, "Yes. Ithink that one can request an army not to kill someone by gesturingfor safe conduct, because as far as I am concerned, gesture has thesame status as speech. I have heard that Abdullah ibn Abbas said,'There is no people who betray a pledge, but that Allah gives theirenemies power over them.' "
USC-MSA web (English) reference: Book 21, Hadith 12
Arabic reference: Book 21, Hadith 973