Musnad Ahmad 25:940

Aswad ibn Amir narrated to us, Sharik narrated to us, from Abu Ishaq, from Sa'id ibn Jubayr, from Ibn Abbas: That the Prophet, peace and blessings of Allah be upon him, used to recite in the dawn prayer on Friday: "Alif-Lam-Mim. The revelation of the Book..." (As-Sajdah), and "Has there [not] come upon man a period of time..." (Al-Insan).