Musnad Ahmad 27:1679

Ya'qub narrated to us, my father narrated to us, from Salih, Nafi' narrated to us, that Abdullah informed him that the mosque, during the time of the Messenger of Allah, may Allah bless him and grant him peace, was built of mud bricks, its roof was of palm branches, and its pillars were of palm wood. Abu Bakr did not add anything to it. Umar added to it and built it upon its construction during the time of the Messenger of Allah, may Allah bless him and grant him peace, with mud bricks and palm branches, and he restored its pillars as wood. Then Uthman altered it and added a great addition to it. He built its wall with carved stones and gypsum, and he made its pillars of carved stone, and he roofed it with teak.