Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said, “Who will depart with this letter of mine to Caesar and thus he will have Paradise?” A man among the people said, “Even if I am not killed?” The Prophet said, “Even if you are not killed.” The man departed with it and met Caesar as he came to the Sacred House. When Caesar finished the letter, he took it and summoned the heads of the priesthood. He read it and commanded the palace doors to be locked, and then he commanded someone to announce, “Caesar has surely followed Muhammad and abandoned Christianity!” His soldiers confronted him with arms until they surrounded his palace. Caesar said of the Messenger of Allah, “Do you see I am fearful of my kingdom?” Then, he commanded someone to announce, “Surely, Caesar is pleased with you, for he only told you that he might examine how perseverant you are in your religion, so turn back!” The soldiers withdrew, and Caesar wrote to the Messenger of Allah, saying, “Indeed, I am a Muslim,” and he sent him some gold coins. When he read the letter, the Prophet said, “The enemy of Allah has lied. He is not a Muslim, but he is upon Christianity.”
Source: Ṣaḥīḥ Ibn Ḥibbān 4504
Grade: Sahih (authentic) according to Al-Arna’ut
عَنْ أَنَسِ بْنِ مَالِكٍ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَنْ يَنْطَلِقُ بِصَحِيفَتِي هَذِهِ إِلَى قَيْصَرَ وَلَهُ الْجَنَّةُ فَقَالَ رَجُلٌ مِنَ الْقَوْمِ وَإِنْ لَمْ أُقْتَلُ قَالَ وَإِنْ لَمْ تُقْتَلْ فَانْطَلَقَ الرَّجُلُ بِهِ فَوَافَقَ قَيْصَرَ وَهُوَ يَأْتِي بَيْتَ الْمَقْدِسِ فَلَمَّا انْتَهَى قَيْصَرُ إِلَى الْكِتَابِ أَخَذَهُ ثُمَّ دَعَا رَأْسَ الْجَاثَلِيقِ فَأَقْرَأَهُ فَأَمَرَ قَيْصَرُ بِأَبْوَابٍ قَصْرِهِ فغُلِّقَت ثُمَّ أَمَرَ مُنَادِيًا يُنَادِي أَلَا إِنَّ قَيْصَرَ قَدِ اتَّبَعَ مُحَمَّدًا صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَتَرَكَ النَّصْرَانِيَّةَ فَأَقْبَلَ جُنْدُهُ وَقَدْ تَسَلَّحُوا حَتَّى أَطَافُوا بِقَصْرِهِ فَقَالَ لِرَسُولِ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَدْ تَرَى أَنِّي خَائِفٌ عَلَى مَمْلَكَتِي ثُمَّ أَمَرَ مُنَادِيًا فَنَادَى أَلَا إِنَّ قَيْصَرَ قَدْ رَضِيَ عَنْكُمْ وَإِنَّمَا خَبَرَكُمْ لَيَنْظُرُ كَيْفَ صَبْرُكُمْ عَلَى دِينِكُمْ فَارْجِعُوا فَانْصَرَفُوا وَكَتَبَ قَيْصَرُ إِلَى رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِنِّي مُسْلِمٌ وَبَعَثَ إِلَيْهِ بِدَنَانِيرَ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ حِينَ قَرَأَ الْكِتَابَ كَذَبَ عَدُوُّ اللهِ لَيْسَ بِمُسْلِمٍ وَهُوَ عَلَى النَّصْرَانِيَّةِ
4504 صحيح ابن حبان باب في الخلافة والإمارة ذكر الإباحة للإمام قبول الهدايا من المشركين إذا طمع في إسلامهم
10/358 المحدث شعيب الأرناؤوط خلاصة حكم المحدث إسناده صحيح في تخريج صحيح ابن حبان