Sunan Ibn Majah, Volume 3, Book 21, Hadith 2691 (DarusSalam) ⓘ
It was narrated that Anas bin Malik said: “A man brought the killer of his relative to the Messenger of Allah and the Messenger of Allah said: 'Pardon him,' but the refused. He said: 'Take the blood money,' but he refused. He said: 'Go and kill him, but then you will be like him.’ Someone caught up with him and reminded him that the Messenger of Allah had said: 'Go and kill him, but then you will be like him.’ So he let him go.
حَدَّثَنَا أَبُو عُمَيْرٍ، عِيسَى بْنُ مُحَمَّدٍ النَّحَّاسُ وَعِيسَى بْنُ يُونُسَ وَالْحُسَيْنُ بْنُ أَبِي السَّرِيِّ الْعَسْقَلاَنِيُّ قَالُوا حَدَّثَنَا ضَمْرَةُ بْنُ رَبِيعَةَ، عَنِ ابْنِ شَوْذَبٍ، عَنْ ثَابِتٍ الْبُنَانِيِّ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ أَتَى رَجُلٌ بِقَاتِلِ وَلِيِّهِ إِلَى رَسُولِ اللَّهِ صلى الله عليه وسلم فَقَالَ النَّبِيُّ صلى الله عليه وسلم " اعْفُ " . فَأَبَى فَقَالَ " خُذْ أَرْشَكَ " . فَأَبَى . قَالَ " اذْهَبْ فَاقْتُلْهُ فَإِنَّكَ مِثْلُهُ " . قَالَ فَلُحِقَ بِهِ فَقِيلَ لَهُ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَدْ قَالَ " اقْتُلْهُ فَإِنَّكَ مِثْلُهُ " . فَخَلَّى سَبِيلَهُ . قَالَ فَرُئِيَ يَجُرُّ نِسْعَتَهُ ذَاهِبًا إِلَى أَهْلِهِ . قَالَ كَأَنَّهُ قَدْ كَانَ أَوْثَقَهُ .
also referenced under: Hadith 2691 (Reference) & Book 21, Hadith 2793 (In-Book)