Hadith 4008 - The Book of Fighting [The Prohibition of Bloodshed] - Sunan An-Nasa'i - سنن النسائي - Collection of Actions, Sayings and Teachings of Prophet Muhammad (صلى الله عليه و سلم) - Kutub as-Sittah

37. The Book of Fighting [The Prohibition of Bloodshed] - كتاب تحريم الدم

2) Chapter: The Gravity of the Sin of Shedding Blood

It was narrated that Mujalid bin 'Awf said: "I heard Kharijah bin Zaid bin Thabit narrate that his father said: (The Verse) 'And whoever kills a believer intentionally, his recompense is Hell' was revealed and we became worried about it. Then the Verse in Al-Furqan 'And those who invoke not any other ilah (god) along with Allah, or kill such person as Allah has forbidden, except by right.' was revealed."

Reference: 4008
English reference: Vol. 5, Book 37, Hadith 4013
In-book reference: Book 37, Hadith 43
Grade: Hasan (Darussalam)
Read this hadith from Darussalam Collection

2) باب تَعْظِيمِ الدَّمِ ‏‏

أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، عَنْ مُسْلِمِ بْنِ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ إِسْحَاقَ، عَنْ أَبِي الزِّنَادِ، عَنْ مُجَالِدِ بْنِ عَوْفٍ، قَالَ سَمِعْتُ خَارِجَةَ بْنَ زَيْدِ بْنِ ثَابِتٍ، يُحَدِّثُ عَنْ أَبِيهِ، أَنَّهُ قَالَ نَزَلَتْ ‏{‏ وَمَنْ يَقْتُلْ مُؤْمِنًا مُتَعَمِّدًا فَجَزَاؤُهُ جَهَنَّمُ خَالِدًا فِيهَا ‏}‏ أَشْفَقْنَا مِنْهَا فَنَزَلَتِ الآيَةُ الَّتِي فِي الْفُرْقَانِ ‏{‏ وَالَّذِينَ لاَ يَدْعُونَ مَعَ اللَّهِ إِلَهًا آخَرَ وَلاَ يَقْتُلُونَ النَّفْسَ الَّتِي حَرَّمَ اللَّهُ إِلاَّ بِالْحَقِّ ‏}‏ ‏.‏