أَخْبَرَنَا عَبْدُ اللَّهِ بْنُ سَعِيدٍ ، حَدَّثَنَا أَبُو بَكْرِ بْنُ عَيَّاشٍ ، عَنْ عَاصِمٍ ، عَنْ أَبِي وَائِلٍ ، عَنِ ابْنِ مُعَيْزٍ السَّعْدِيِّ ، قَالَ : خَرَجْتُ أُسْفِرُ فَرَسًا لِي مِنَ السَّحَرِ فَمَرَرْتُ عَلَى مَسْجِدٍ مِنْ مَسَاجِدِ بَنِي حَنِيفَةَ، فَسَمِعْتُهُمْ يَشْهَدُونَ أَنَّ مُسَيْلَمَةَ رَسُولُ اللَّهِ، فَرَجَعْتُ إِلَى عَبْدِ اللَّهِ بْنِ مَسْعُودٍ فَأَخْبَرْتُهُ، فَبَعَثَ إِلَيْهِمْ الشُّرَطَ، فَأَخَذُوهُمْ، فَجِيءَ بِهِمْ، إِلَيْهِ فَتَابَ الْقَوْمُ وَرَجَعُوا عَنْ قَوْلِهِمْ، فَخَلَّى سَبِيلَهُمْ، وَقَدَّمَ رَجُلًا مِنْهُمْ يُقَالُ لَهُ : عَبْدُ اللَّهِ بْنُ النَّوَاحَةِ، فَضَرَبَ عُنُقَهُ، فَقَالُوا لَهُ : تَرَكْتَ الْقَوْمَ وَقَتَلْتَ هَذَا؟، فَقَالَ : إِنِّي كُنْتُ عِنْدَ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ جَالِسًا إِذْ دَخَلَ هَذَا وَرَجُلٌ وَافِدَيْنِ مِنْ عِنْدِ مُسَيْلَمَةَ، فَقَالَ لَهُمَا رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ : " أَتَشْهَدَانِ أَنِّي رَسُولُ اللَّهِ؟ "، فَقَالَا لَهُ : تَشْهَدُ أَنْتَ أَنَّ مُسَيْلَمَةَ رَسُولُ اللَّهِ، فَقَالَ :" آمَنْتُ بِاللَّهِ وَرُسُلِهِ، لَوْ كُنْتُ قَاتِلًا وَفْدًا، لَقَتَلْتُكُمَا ".
فَلِذَلِكَ قَتَلْتُهُ.
وَأَمَرَ بِمَسْجِدِهِمْ فَهُدِمَ

Abdullah bin Saeed told us, Abu Bakr bin Ayyash told us, on the authority of Asim, on the authority of Abu Wael, on the authority of Ibn Muiz al-Saadi, he said: I went out on a journey with my horse of magic, so I passed by one of the mosques of Banu Hanifa, and I heard them testify that Musailama was the Messenger of God, so I returned To Abdullah bin Masoud and I informed him, so he sent police to them, and they took them, and they were brought to him, and the people repented and turned away from What they said, so he let them go, and brought a man from them called: Abdullah bin Al-Nawahah. He beheaded him, and they said to him: You left the people. And you killed this man? He said: I was sitting with the Messenger of God, may God bless him and grant him peace, when this man and a man entered, coming from Musaylimah. Then the Messenger of God, may God bless him and grant him peace, said to them: “Do you bear witness that I am the Messenger of God?” So they said to him: You bear witness that Musaylimah is the Messenger of God. He said: “I believe in God and His Messengers. If I were to kill a delegation, I would kill you both.”
That's why I killed him.
He ordered their mosque to be demolished