Musannaf Ibn Abi Shayba 18:821

Abu Bakr narrated to us, he said: Shababa narrated to us, from Shu'bah, from al-Hakam and Hammad, that they both said: Regarding a man who kills a man, and a woman pardons [the killer]: They both said: Whoever pardons, whether a man or a woman, then it wards off the blood money from him.