When Muhammad entered Mecca, he ordered his followers only to fight those who refused to surrender to him, except certain people who were to be executed whether they surrendered or not. In our earliest detailed biographical source on the fall of Mecca, Ibn Ishaq lists eight people who were to receive the death penalty. The charges against four of the eight were "insulting Muhammad." One of the four critics was eventually pardoned; the others were killed.
Politicians, the media, and Muslim groups assure us that Muhammad never retaliated against people who insulted him. Too bad these modern apologists weren't there to tell Muhammad how tolerant they would one day imagine him to be.
Here's the passage from Ibn Ishaq, with details on the critics underlined. Pass it on.