Musannaf Ibn Abi Shayba 3:3109

Hameed ibn Abd al-Rahman narrated to us, from Hasan ibn Salih, from Ibrahim ibn al-Muhajir, from Abu Bakr ibn Amr ibn Utbah al-Zuhri, who said: Al-Hajjaj delayed the Friday prayer. When he prayed it, Abu Juhayfah prayed it with him. Then he (Abu Juhayfah) stood up and connected it with two rak'ahs. Then he said: "O Abu Bakr, I call you to witness that it is the Asr (prayer)."