Messenger of Allah ﷺ wrote a letter to Caesar saying, "If you reject Islam, you will be responsible for the sins of the tillers (i.e. your people).  

أَخْبَرَهُ أَنَّ رَسُولَ اللَّهِ ﷺ كَتَبَ إِلَى قَيْصَرَ وَقَالَ فَإِنْ تَوَلَّيْتَ فَإِنَّ عَلَيْكَ إِثْمَ الأَرِيسِيِّينَ