Musannaf Ibn Abi Shayba 3:1818

4195. Abda narrated to us, from al-A’mash, from Ibrahim al-Taymi, who said: I used to recite [the Quran] to my father, and he would recite to me on the road. He would pass by a prostration [verse], so he would prostrate. I said to him, "Do you prostrate on the road?" He said, "Yes."