Musannaf Ibn Abi Shayba 18:825

Abu Bakr narrated to us, he said: Abda ibn Sulayman narrated to us, from Sa'id ibn Muslim, from al-Sha'bi, regarding a man who was killed and left behind his daughter, his sister, and his two wives, and one of the two wives pardoned [the killer]. Al-Sha'bi said: A woman has no [right of] pardon, except for a woman who has a close blood relation and a share in the inheritance.