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 رَسُولَ اللَّهِ ﷺ أَمَرَ بِقَتْلِهِ وَكَانَ عَيْنًا لِأَبِي سُفْيَانَ فَمَرَّ بِمَجْلِسِ الْأَنْصَارِ فَقَالَ إِنِّي مُسْلِمٌ فَذَهَبُوا بِهِ إِلَى رَسُولِ اللَّهِ ﷺ فَقَالُوا إِنَّهُ يَزْعُمُ أَنَّهُ مُسْلِمٌ فَقَالَ «إِنَّ مِنْكُمْ رِجَالًا نَكِلُهُمْ إِلَى إِيمَانَهِمْ مِنْهُمْ فُرَاتُ بْنُ حَيَّانَ»