The Messenger of Allah ﷺ said, "I will not pardon anyone who kills after having accepted the blood-money."
حدثنا عفان حدثنا حماد بن سلمة أخبرنا مطر عن رجل أحسبه الحسن
أن رسول الله ﷺ قال لا أعفي من قتل بعد أخذه الدية
Its isnad is daif, due to the anonymity of the narrator who transmitted from Jabir, and Hammad's uncertainty about the identity of Matar's teacher. Abu Dawud Tayalisi related it (243, no. 1763) from "a man," without this uncertainty, and similarly to Ahmad's version, Abu Dawud Sijistani related it in his Sunan (4/173, no. 4507). Ibn Hajar cited it as supporting evidence in Fath al-Bari (12/209) and said, "It is disconnected." Nevertheless, the scholars accepted this hadith and all acted upon it.