Musnad Ahmad 459:11

Abu al-Ala’, who is al-Hasan ibn Siwar, narrated to us, he said: Layth narrated to us, from Mu’awiyah, from Sa’id ibn Suwayd, from ‘Abd al-A’la ibn Hilal al-Sulami, from ‘Irbad ibn Sariyah, he said: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "Indeed, I am the servant of Allah, the Seal of the Prophets." He mentioned the like of it, and added in it: "Indeed, the mother of the Messenger of Allah, may Allah bless him and grant him peace, saw when she gave birth to him a light from which the palaces of Ash-Sham were illuminated."