Abu Hurarirah reported the Apostle of Allaah ﷺ as saying “A Muslim ruler is shield by which a battle is fought.”  

قَالَ رَسُولُ اللَّهِ ﷺ إِنَّمَا الإِمَامُ جُنَّةٌ يُقَاتَلُ بِهِ  

The Quraysh sent me to the Messenger of Allah ﷺ, and when I saw the Messenger of Allah ﷺ, Islam was cast into my heart, so I said: Messenger of Allah, I swear by Allah, I shall never return to them. The Messenger of Allah ﷺ replied: I do not break a covenant or imprison messengers, but return, and if you feel the same as you do just now, come back. So I went away, and then came to the Prophet ﷺ and accepted Islam. The narrator Bukair said: He informed me that Abu Rafi' was a Copt. Abu Dawud said: This was valid in those days, but today it is not valid.  

أَخْبَرَهُ قَالَ بَعَثَتْنِي قُرَيْشٌ إِلَى رَسُولِ اللَّهِ ﷺ فَلَمَّا رَأَيْتُ رَسُولَ اللَّهِ ﷺ أُلْقِيَ فِي قَلْبِيَ الإِسْلاَمُ فَقُلْتُ يَا رَسُولَ اللَّهِ إِنِّي وَاللَّهِ لاَ أَرْجِعُ إِلَيْهِمْ أَبَدًا فَقَالَ رَسُولُ اللَّهِ ﷺ إِنِّي لاَ أَخِيسُ بِالْعَهْدِ وَلاَ أَحْبِسُ الْبُرُدَ وَلَكِنِ ارْجِعْ فَإِنْ كَانَ فِي نَفْسِكَ الَّذِي فِي نَفْسِكَ الآنَ فَارْجِعْ قَالَ فَذَهَبْتُ ثُمَّ أَتَيْتُ النَّبِيَّ ﷺ فَأَسْلَمْتُ قَالَ بُكَيْرٌ وَأَخْبَرَنِي أَنَّ أَبَا رَافِعٍ كَانَ قِبْطِيًّا