عَنْ عَلِيٍّ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ الْمُؤْمِنُونَ تَتَكَافَأُ دِمَاؤُهُمْ وَهُمْ يَدٌ عَلَى مَنْ سِوَاهُمْ يَسْعَى بِذِمَّتِهِمْ أَدْنَاهُمْ أَلَا لَا يُقْتَلُ مُؤْمِنٌ بِكَافِرٍ وَلَا ذُو عَهْدٍ فِي عَهْدِهِ
Narrated by Sayyiduna Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: The blood of the believers is equal among themselves, they are united in cooperation against their enemies, even the lowest-ranking Muslim has the right to the covenant of all Muslims. Beware! A believer will not be killed in retaliation for a disbeliever, and no dhimmi will be killed during his covenant.