Abil Shuraih Al-Khaza'i (RAA) narrated that The Messenger of Allah (ﷺ) said:
"If the relative of one of you is killed after my speech, his family has one of two choices: 'Either they take his Diyah or kill the killer." Related by Abu Dawud and An-Nasa'i. (DE)
English reference (DE): Book 9, Hadith 1216 (DE)
Arabic reference (DE): Book 9, Hadith 1186 (DE)