Musannaf Ibn Abi Shayba 3:4465

'Abdah narrated to us, from Sa'id, from Qatadah, from Zurarah, from Sa'id ibn Hisham, from his father, from 'Aishah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) would not perform the taslim (salutation) during the two rak'ahs of the witr.