Musnad Ahmad 27:13

Hushaym narrated to us, Isma'il ibn Abi Khalid informed us, Abu Ishaq narrated to us, from Sa'id ibn Jubayr, who said: I was with Ibn 'Umar when he departed from 'Arafat, then he came to Jam' (Muzdalifah) and prayed Maghrib and Isha. When he finished, he said: "The Messenger of Allah, peace and blessings of Allah be upon him, did in this place just as I have done." Hushaym said once: "Then he prayed Maghrib with us, then he said: 'The prayer,' and he prayed two rak'ahs, then he said: 'Thus did the Messenger of Allah, peace and blessings of Allah be upon him, do with us in this place.'"