Musnad Ahmad 27:165

Yahya narrated to us, Hisham ibn Urwah narrated to us, my father informed me, Ibn Umar informed me, he said: The Messenger of Allah, may Allah bless him and grant him peace, said: "Do not seek to perform your prayer at the rising of the sun, nor at its setting, for it rises between the two horns of a devil. So when the edge of the sun appears, do not pray until it fully emerges, and when the edge of the sun sets, do not pray until it disappears."