Musnad Ahmad 1224
It was narrated that ‘Abeedah said:
‘Ali (رضي الله عنه) said to the people of an-Nahrawan: Among them is a man with a defective arm - or an incomplete arm, or a deformed arm. If you could exercise restraint I would have told you what Allah promised on the lips of His Prophet (ﷺ)  to those who kill them. `Abeedah said: I said to ‘Ali (رضي الله عنه): Did you hear him? He said: Yes, by the Lord of the Ka`bah; and he swore this oath three times.
حَدَّثَنَا يَزِيدُ، أَنْبَأَنَا هِشَامٌ، عَنْ مُحَمَّدٍ، عَنْ عَبِيدَةَ، قَالَ قَالَ عَلِيٌّ لِأَهْلِ النَّهْرَوَانِ مِنْهُمْ رَجُلٌ مَثْدُونُ الْيَدِ أَوْ مُودَنُ الْيَدِ أَوْ مُخْدَجُ الْيَدِ لَوْلَا أَنْ تَبْطَرُوا لَأَنْبَأْتُكُمْ مَا قَضَى اللَّهُ عَلَى لِسَانِ نَبِيِّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لِمَنْ قَتَلَهُمْ قَالَ عَبِيدَةُ فَقُلْتُ لِعَلِيٍّ رَضِيَ اللَّهُ عَنْهُ آنْتَ سَمِعْتَهُ قَالَ نَعَمْ وَرَبِّ الْكَعْبَةِ يَحْلِفُ عَلَيْهَا ثَلَاثًا‏.‏