Musnad Ahmad 27:2013

He said: I read to my father, Hammad ibn Khalid narrated to us, from Ibn Abi Dhi'b, from al-Zuhri, from Salim, from his father, that he "prayed with the Messenger of Allah, may Allah bless him and grant him peace, at al-Muzdalifah the Maghrib and the Isha with one iqamah, one iqamah; he combined them."