It is reported from Urwah (may Allah have mercy on him) that there is no diyah (blood money) upon the 'aqilah (paternal kinsmen) in deliberate killing, unless they wish (to pay it); upon them is the diyah for accidental killing.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16362