Musannaf Ibn Abi Shayba 3:3961

Abu Khalid al-Ahmar narrated to us, from Uthman ibn Hakim, from Sa’id ibn Yasar, from Ibn Abbas: That the Prophet, peace and blessings of Allah be upon him, used to recite in the two rak'ahs of the dawn prayer: in the first, "Say, 'We have believed in Allah and in what was revealed to us...'" [Al-Baqarah: 136], the verse. And in the second, "Come to a word that is equitable between us and you..." [Al-Imran: 64].