The Killing of Abu Afak

FROM THE KITAB AL TABAQAT AL KABIR (BOOK OF THE MAJOR CLASSES), Volume 2, BY IBN SA'D, page 31:
"Then occurred the "sariyyah" [raid] of Salim Ibn Umayr al-Amri against Abu Afak, the Jew, in [the month of] Shawwal in the beginning of the twentieth month from the hijrah [immigration from Mecca to Medina in 622 AD], of the Apostle of Allah. Abu Afak, was from Banu Amr Ibn Awf, and was an old man who had attained the age of one hundred and twenty years. He was a Jew, and used to instigate the people against the Apostle of Allah, and composed (satirical) verses [about Muhammad].
Salim Ibn Umayr who was one of the great weepers and who had participated in Badr, said, "I take a vow that I shall either kill Abu Afak or die before him. He waited for an opportunity until a hot night came, and Abu Afak slept in an open place. Salim Ibn Umayr knew it, so he placed the sword on his liver and pressed it till it reached his bed. The enemy of Allah screamed and the people who were his followers, rushed to him, took him to his house and interred him.

FROM ALI DASHTI'S "23 YEARS: A STUDY OF THE PROPHETIC CAREER OF MOHAMMAD", page 100:
"Abu Afak, a man of great age (reputedly 120 years) was killed because he had lampooned Mohammad. The deed was done by Salem b. Omayr at the behest of the Prophet, who had asked, "Who will deal with this rascal for me?" The killing of such an old man moved a poetess, Asma b. Marwan, to compose disrespectful verses about the Prophet, and she too was assassinated."