Musnad Ahmad 26:496

Abu Mu'awiyah and Ibn Numayr narrated to us, they said: Al-A'mash narrated to us, from 'Umarah, from 'Abd al-Rahman ibn Yazid, from 'Abdullah, who said: "I never saw the Messenger of Allah, may Allah bless him and grant him peace, perform any prayer except at its appointed time, except for two prayers: the Maghrib prayer and the 'Isha' prayer at Jam' (Muzdalifah), and he performed the Fajr prayer on that day before its (usual) appointed time." Ibn Numayr said: "The two 'Isha's (Maghrib and 'Isha'), for he performed them both together at Jam'."