Ibn Salamah bin al-Akwa' narrates from his father (Sayyiduna Salamah bin al-Akwa' (may Allah be pleased with him)) that during a journey a spy of the polytheists came to the Prophet (peace and blessings be upon him). He sat with the Companions (may Allah be pleased with them), talking, and then slipped away. He (peace and blessings be upon him) said: "Catch him and kill him." The narrator says: I killed him and took his belongings.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18436
Harithah bin Mudarrib narrates from Furat bin Hayyan (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) had ordered him to be killed; he was a spy for Abu Sufyan and, I think he said, an ally of a man from the Ansar. He passed by a gathering of the Ansar and said: "I am a Muslim." One of them said: O Messenger of Allah (peace and blessings be upon him), he says: I am a Muslim. The Messenger of Allah (peace and blessings be upon him) said: "Among them are some men whom we entrust to their faith, and among them is Furat bin Hayyan."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18437