Tortured - what did he do to him?
From Wikipedia, a somewhat neutral source:
Ibn Hisham writes about Kinana ibn al-Rabi
Kinana al-Rabi, who had the custody of the treasure of Banu Nadir, was brought to the apostle who asked him about it. He denied that he knew where it was. A Jew came (Tabari says "was brought"), to the apostle and said that he had seen Kinana going round a certain ruin every morning early. When the apostle said to Kinana, "Do you know that if we find you have it I shall kill you?" He said "Yes". The apostle gave orders that the ruin was to be excavated and some of the treasure was found. When he asked him about the rest he refused to produce it, so the apostle gave orders to al-Zubayr Al-Awwam, "Torture him until you extract what he has." So he kindled a fire with flint and steel on his chest until he was nearly dead. Then the apostle delivered him to Muhammad b. Maslama and he struck off his head, in revenge for his brother Mahmud
Al-Mubarakpuri maintains that al-Rabi was bound by agreements between Muhammad and Khaybar to not conceal anything from the Muslims. He was exceuted, al-Mubarakpuri concludes, for breaching the agreement. Montgomery Watt supports the view that he was executed for concealing the treasure. Shibli Nomani, however, argues that Kinana was put to death because he had killed Mahmud, the brother of Muhammad b. Maslama. Nomani also casts doubt on the accuraccy of the story due to its sources (see section below).[5]
Authenticity
The story of al-Rabi narrated by Ibn Hisham has been taken from Ibn Ishaq. Ibn Ishaq, however, doesn't specify any source for this story. According to Nomani, tradionists have stated that Ibn Ishaq probably borrowed this story from the contemporary descendents of al-Rabi's tribe.
Nomani also casts doubt on the story on the basis of its inconsistency with Muhammad's other actions. He doubts Muhammad would have tortured al-Rabi, as he forgave the Jewess Rayhana bint Amr ibn Khunafa after the she tried to poison him.
Rashna's comments: Rayhana was a Jewish woman who he raped, er married so she naturally wanted revenge. So much sordid stuff in this guy's life. Sheet!
Topic: Was Prophet Muhammad a gold digger?