look up Asma bint Marwan
Then (occurred) the sariyyah of `Umayr ibn `Adi Ibn Kharashah al-Khatmi against `Asma’ Bint Marwan, of Banu Umayyah Ibn Zayd, when five nights had remained from the month of Ramadan, in the beginning of the nineteenth month from the hijrah of the apostle of Allah. `Asma’ was the wife of Yazid Ibn Zayd Ibn Hisn al-Khatmi. She used to revile Islam, offend the prophet and instigate the (people) against him. She composed verses. Umayr Ibn Adi came to her in the night and entered her house. Her children were sleeping around her. There was one whom she was suckling. He searched her with his hand because he was blind, and separated the child from her. He thrust his sword in her chest till it pierced up to her back. Then he offered the morning prayers with the prophet at al-Medina. The apostle of Allah said to him: “Have you slain the daughter of Marwan?” He said: “Yes. Is there something more for me to do?” He [Muhammad] said: “No two goats will butt together about her”. This was the word that was first heard from the apostle of Allah. The apostle of Allah called him `Umayr, “basir” (the seeing).[8]
http://en.wikipedia.org/wiki/’Asma’_bint_Marwan
RE: Asma bint Marwan
According to the Wikipedia source you mentioned....
“The story of her death by command of the Islamic prophet Muhammad, after she opposed him with poetry and provoked other pagans to commit violence against him, can be found in the s’ra material collected by Ibn Ishaq and Ibn Sa’d”
BUT HERE’s THE KICKER:
“Some classical and post-classical hadith scholars such as Al-Albani, Majdi, and Al-Jawzi have rejected the story, with some declaring it as fabrication, pointing out in their arguments that the chains of transmission by which the story was transmitted are all weak.”
It’s going to be very hard to argue that Muhammad did this deed when Muslims can always respond that this story is NOT considered sacred text and is considered a fabrication by enemies of Muhammad to make him look like a monster (BTW, I’ve heard Muslims make this claim to defend Muhammad before ).