The Messenger of Allah ﷺ commanded to kill him: he was a spy of AbuSufyan and an ally of a man of the Ansar. He passed a circle of the Ansar and said: I am a Muslim. A man from the Ansar said, Messenger of Allah, he is saying that he is a Muslim. The Messenger of Allah ﷺ said: There are people among you in whose faith we trust. Furat ibn Hayyan is one of them. (Using translation from Abū Dāʾūd 2652)   

أَنَّ النَّبِيَّ ﷺ أَمَرَ بِقَتْلِهِ وَكَانَ عَيْنًا لِأَبِي سُفْيَانَ وَحَلِيفًا فَمَرَّ بِحَلْقَةِ الْأَنْصَارِ فَقَالَ إِنِّي مُسْلِمٌ قَالُوا يَا رَسُولَ اللهِ إِنَّهُ يَزْعُمُ أَنَّهُ مُسْلِمٌ فَقَالَ إِنَّ مِنْكُمْ رِجَالًانَكِلُهُمْ إِلَى إِيمَانِهِمْ مِنْهُمْ فُرَاتُ بْنُ حَيَّانَ