Musnad Abu Ya'la al-Mawsili 2:20

Abu Khaythama narrated to us, Yahya bin Sa'id al-Qattan narrated to us, from Shu'bah, who said: Qatada narrated to me, from Abu al-'Aliyah, from Ibn 'Abbas, who said: Men narrated to me, and the most pleasing of them to me was 'Umar, that the Messenger of Allah (may Allah bless him and grant him peace) forbade prayer after the dawn [prayer] until the sun rises, and after the afternoon [prayer] until the sun sets.