Musnad Ahmad 31:259

Ishaq ibn Isa narrated to us, Abdullah ibn Lahi'ah ibn Uqbah narrated to us, Bukayr ibn Abdullah ibn al-Ashajj narrated to us, from Abd al-Malik ibn Sa'id ibn Suwayd al-Sa'idi, from Abu Sa'id al-Khudri, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Gabriel led me in prayer. He prayed the Dhuhr prayer when the sun had passed the meridian, and he prayed the Asr prayer when the shadow was the length of a man. He prayed the Maghrib prayer when the sun had set, and he prayed the Isha prayer when the twilight had disappeared, and he prayed the Fajr prayer when the dawn had broken. Then he came to him the next day, and he prayed the Dhuhr prayer when the shadow of everything was equal to it, and he prayed the Asr prayer when the shadow was two lengths of a man. He prayed the Maghrib prayer when the sun had set, and he prayed the Isha prayer until the first third of the night, and he prayed the Subh (Fajr) prayer when the sun was about to rise. Then he said: 'The prayer is between these two times.'"