I asked Ibn Abbas, "Is there any repentance for someone who kills a believer intentionally?"He replied, "No."So I recited to him the verse in 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].He said, "This is a Meccan verse, abrogated by a Medinan verse, "And whoever kills a believer intentionally, his recompense is Hell" [Nisa 4:93]."
أخبرنا عمرو بن علي قال حدثنا يحيى قال حدثنا ابن جريج قال حدثني القاسم بن أبي بزة
قلت لابن عباس هل لمن قتل مؤمنا متعمدا من توبة قال لا وقرأت عليه الآية التي في الفرقان {والذين لا يدعون مع الله إلها آخر ولا يقتلون النفس التي حرم الله إلا بالحق} قال هذه آية مكية نسختها آية مدنية {ومن يقتل مؤمنا متعمدا فجزاؤه جهنم}
Muslim narrated it in tafsir, hadith 20/3023, from the hadith of Yahya Qattan. Bukhari narrated it in tafsir, chapter of His saying, "Those who do not invoke another god besides Allah..." etc., hadith 4762, from the hadith of Ibn Jurayj, from him. It is also in Kubra, hadith 3464.