It is narrated from Abu Shurayh Ka'bi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "If someone’s relative is killed, then his heirs have two options. If they wish, they may take blood money, and if they wish, they may take retribution (qisas)."
Hadith Referenceمسند الإمام الشافعي / كتاب القتل والقصاص والديات والقسامة / 1630
Hadith Takhrijصحیح: اخرجه البيهقي في المعرفة السنن والآثار (4850)۔