Musnad Ahmad 14:1

Ali ibn Bahr narrated to us, Muhammad ibn Salamah narrated to us, from Muhammad ibn Ishaq, from Yahya ibn Abbad, from his father Abbad ibn Abdullah ibn al-Zubayr, who said: Al-Harith ibn Khuzaymah brought these two verses from the end of [Surah] Bara’ah: "There has certainly come to you a Messenger from among yourselves" [At-Tawbah: 128] to Umar ibn al-Khattab. He said, "Who is with you regarding this?" He said, "I do not know, by Allah, except that I bear witness that I heard it from the Messenger of Allah (may Allah bless him and grant him peace), and I comprehended it, and I memorized it." Umar said, "And I bear witness that I heard it from the Messenger of Allah (may Allah bless him and grant him peace)." Then he said, "If it were three verses, I would have made it a separate surah. So look for a surah of the Qur’an and place it therein." So I placed it at the end of [Surah] Bara’ah.