I asked Ibn Abbas, "Is there any repentance for someone who kills a believer intentionally?"He replied, "No."So I recited to him this verse from Surah al-Furqan, "And those who do not invoke another god alongside Allah, nor kill the soul which Allah has forbidden except by right" [Furqan 25:68], to the end of the verse.He said, "This is a Meccan verse, abrogated by a Medinan verse, "And whoever kills a believer intentionally, his recompense is Hell, abiding eternally therein" [Nisa 4:93].
قلت لابن عباس: ألمن قتل مؤمنا متعمدا من توبة؟ قال: لا. قال: فتلوت عليه هذه الآية التي في الفرقان: {والذين لا يدعون مع الله إلها اخر ولا يقتلون النفس التي حرم الله إلا بالحق} [سورة الفرقان: ٦٨] إلى آخر الآية، قال: هذه آية مكية، نسختها آية مدنية: {ومن يقتل مؤمنا متعمدا فجزاؤه جهنم خلدا}
Bukhari related it in the tafsir (4762), and Muslim in the tafsir (20/3032), both of them through the route of Ibn Jurayj, "Qasim bin Abu Bazza told me, from Saeed bin Jubayr, who said," and he mentioned it. The wording is Muslim's, and Bukhari's wording is similar.