Musannaf Ibn Abi Shayba 3:3258

Abu Usama narrated to us, from Abu 'Awanah, from Hajjaj, from 'Ata', from 'Ubayd ibn 'Umayr, from 'Umar, that he used to say the takbir from the dawn prayer on the day of 'Arafah until the noon prayer of the last of the days of Tashriq.