Musnad Abu Ya'la al-Mawsili 142:2

Abu Bakr ibn Abi Shaybah narrated to us, Waki' narrated to us, from Sufyan, from Zayd al-'Ammi, from Mu'awiyah ibn Qurrah, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Supplication is not rejected between the Adhan and the Iqamah."