Hadith 4001 - 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 Sa'eed bin Jubair said: "I said to Ibn 'Abbas: 'Can a person, who killed a believer intentionally, repent?' He said: 'No.' I recited the Verse from Al-Furqan to him: 'And those who invoke not any other ilah (god) along with Allah, or kill such person as Allah has forbidden, except by right,' he said: 'This Verse was revealed in Makkah and was abrogated by a Verse that was revealed in Al-Madinah: 'And whoever kills a believer intentionally, his recompense is Hell.'"

Reference: 4001
English reference: Vol. 5, Book 37, Hadith 4006
In-book reference: Book 37, Hadith 36
Grade: Sahih (Darussalam)
Read this hadith from Darussalam Collection

2) باب تَعْظِيمِ الدَّمِ ‏‏

أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا ابْنُ جُرَيْجٍ، قَالَ حَدَّثَنِي الْقَاسِمُ بْنُ أَبِي بَزَّةَ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، قَالَ قُلْتُ لاِبْنِ عَبَّاسٍ هَلْ لِمَنْ قَتَلَ مُؤْمِنًا مُتَعَمِّدًا مِنْ تَوْبَةٍ قَالَ لاَ ‏.‏ وَقَرَأْتُ عَلَيْهِ الآيَةَ الَّتِي فِي الْفُرْقَانِ ‏{‏ وَالَّذِينَ لاَ يَدْعُونَ مَعَ اللَّهِ إِلَهًا آخَرَ وَلاَ يَقْتُلُونَ النَّفْسَ الَّتِي حَرَّمَ اللَّهُ إِلاَّ بِالْحَقِّ ‏}‏ قَالَ هَذِهِ آيَةٌ مَكِّيَّةٌ نَسَخَتْهَا آيَةٌ مَدَنِيَّةٌ ‏{‏ وَمَنْ يَقْتُلْ مُؤْمِنًا مُتَعَمِّدًا فَجَزَاؤُهُ جَهَنَّمُ ‏}‏ ‏.‏