Musnad Ahmad 1340
It was narrated that `Abdullah bin Sabu’ said:
‘Ali (رضي الله عنه) addressed us and said: By the One Who split the seed and created the soul, this (his beard) will be soaked from this (his head, i.e., his beard would be soaked with blood from a wound in his head). He said: Tell us who he is. By Allah, we will eliminate him - or we will eliminate his family. He said: I adjure you by Allah not to kill anyone except the one who kills me. They said: If you know that, then appoint a successor. He said: No, rather I shall leave you as the Messenger of Allah (ﷺ) left you.
حَدَّثَنَا أَسْوَدُ بْنُ عَامِرٍ، أَنْبَأَنَا أَبُو بَكْرٍ، عَنِ الْأَعْمَشِ، عَنْ سَلَمَةَ بْنِ كُهَيْلٍ، عَنْ عَبْدِ اللَّهِ بْنِ سَبُعٍ، قَالَ خَطَبَنَا عَلِيٌّ رَضِيَ اللَّهُ عَنْهُ فَقَالَ وَالَّذِي فَلَقَ الْحَبَّةَ وَبَرَأَ النَّسَمَةَ لَتُخْضَبَنَّ هَذِهِ مِنْ هَذِهِ قَالَ قَالَ النَّاسُ فَأَعْلِمْنَا مَنْ هُوَ وَاللَّهِ لَنُبِيرَنَّ عِتْرَتَهُ قَالَ أَنْشُدُكُمْ بِاللَّهِ أَنْ يُقْتَلَ غَيْرُ قَاتِلِي قَالُوا إِنْ كُنْتَ قَدْ عَلِمْتَ ذَلِكَ اسْتَخْلِفْ إِذًا قَالَ لَا وَلَكِنْ أَكِلُكُمْ إِلَى مَا وَكَلَكُمْ إِلَيْهِ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ‏.‏