It is narrated from Abdur Rahman bin Ka'b bin Malik (may Allah have mercy on him) that Ka'b bin al-Ashraf, the Jew, was a poet. He used to satirise the Messenger of Allah (peace and blessings be upon him) and his (peace and blessings be upon him) Companions and incite people against them. So he (peace and blessings be upon him) said: "Who will deal with Ka'b?" When he refused to desist from harming the Messenger of Allah (peace and blessings be upon him) and the Muslims, the Messenger of Allah (peace and blessings be upon him) ordered Sa'd bin Mu'adh, Muhammad bin Maslamah and Abu Isa bin al-Harith (the nephew of Sa'd bin Mu'adh) (may Allah be pleased with them), in a group of five men, and they went to Ka'b. Then the narrator went on to mention the same account as above.
Hadith Referenceالمعجم الكبير للطبراني / باب الكاف / 16205