Musannaf Ibn Abi Shayba 18:624

Abu Bakr narrated to us, he said: Abu Usama narrated to us, from Zakariya, who said: Amir was asked about a military expedition that killed a woman and her master had not freed her, and she had borne him a child. He said: She is a slave-woman; if her master wishes, he may pay [the blood money] on her behalf, and if he wishes, he may surrender her entirely.