Musannaf Ibn Abi Shayba 3:275

Waki’ narrated to us, from ‘Abd al-Hamid ibn Ja’far, from his father, from Tamim ibn Mahmud, from ‘Abd al-Rahman ibn Shibl, who said: The Messenger of Allah (ﷺ) forbade the spreading of the beast (i.e., spreading the forearms on the ground while prostrating).