Musnad Ahmad 456:31

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from al-Zuhri, from 'Ubayd Allah ibn 'Abd Allah ibn 'Utbah, from Zayd ibn Khalid al-Juhani and Abu Hurayrah, who both said: The Messenger of Allah (peace and blessings of Allah be upon him) was asked about the slave woman [who commits adultery]. He mentioned the hadith. And he said in the third or fourth [instance]—al-Zuhri was in doubt—