Sunan An-Nasa'i
Hadith #4000
It was narrated that Sa'eed bin Jubair said:""The people of Al-Kufah differed concerning this Verse: ""And whoever kills a believer intentionally."" So I went to Ibn 'Abbas and asked him, and he said: 'It was revealed among the last of what was revealed, and nothing of it was abrogated after that