Musannaf Ibn Abi Shayba 13:753

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Hammad, from Ibrahim; and from Yunus, from al-Hasan; and from Ash’ath, from al-Sha’bi; they said: The testimony of one woman is permissible in matters which men do not have access to.