The Messenger of Allah ﷺ said, "People of Khuza, you have killed this man from Huzayl, and I will pay his blood-money. But whoever has someone killed after these words of mine, his family has one of two choices, either they accept the blood-money or they take retaliation by killing the killer."
حدثنا مسدد بن مسرهد حدثنا يحيى بن سعيد حدثنا ابن أبي ذئب قال حدثني سعيد بن أبي سعيد قال سمعت
قال رسول الله ﷺ ألا إنكم يا معشر خزاعة قتلتم هذا القتيل من هذيل وإني عاقله فمن قتل له بعد مقالتي هذه قتيل فأهله بين خيرتين أن يأخذوا العقل أو يقتلوا
Its isnad is sahih. Tirmidhi narrated it in the Book of Blood Money, in the chapter on the ruling regarding the guardian of the murdered person's right to retaliation or pardon, hadith no. 1406, from the narration of Yahya bin Saeed Qattan through this route, and he said, hasan sahih.