Musannaf Ibn Abi Shayba 3:1721

Abu Bakr narrated to us, he said: Sufyan ibn ‘Uyaynah narrated to us, from Ibn ‘Ajlan, from Abu ‘Ubayd, he said: I heard him saying: I heard ‘Umar ibn ‘Abd al-‘Aziz at Khanasirah saying when the mu’adhdhin says: "The prayer has been established (qad qamat al-salah)": "Stand up, the prayer has been established."