مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2037
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn 'Abbas that the Messenger of Allah (ﷺ) used to recite in the first rak'ah of Fajr prayer: “We believe in Allah and that which has been sent down to us and that which has been sent down to Ibraheem (Abraham)..." [al-Baqarah 2:136] to the end of the verse; and in the second rak'ah he would recite: "we believe in Allah, and bear witness that we are Muslims (i.e. we submit to Allah)" [Al 'Imran 3:52].
Musnad Ahmad 2038Its isnad is saheeh, Muslim (727)]