It was narrated from Abu Hurairah that the Messenger of Allah ﷺ said: "Whoever helps to kill a believer, even with half a word, he will meet Allah (Subhanahu-wa-Taala) with (the words) written between his eyes, 'He has no hope of the mercy of Allah (Subhanahu-wa-Taala)'."

حَدَّثَنَا عَمْرُو بْنُ رَافِعٍ، حَدَّثَنَا مَرْوَانُ بْنُ مُعَاوِيَةَ، حَدَّثَنَا يَزِيدُ بْنُ زِيَادٍ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ﷺ " مَنْ أَعَانَ عَلَى قَتْلِ مُؤْمِنٍ بِشَطْرِ كَلِمَةٍ لَقِيَ اللَّهَ عَزَّ وَجَلَّ مَكْتُوبٌ بَيْنَ عَيْنَيْهِ آيِسٌ مِنْ رَحْمَةِ اللَّهِ " .