Musannaf Ibn Abi Shayba 3:5987

Abu Dawud al-Tayalisi narrated to us, from al-Hasan ibn Abi Ja'far, from Abu al-Sahba', who said: I saw Mujahid coming from al-Batha', and when he reached the Sacred Mosque, he recited a verse of prostration and prostrated. I mentioned that to 'Ata', and he said: "And what do you find strange about that? The companions of the Messenger of Allah (may Allah bless him and grant him peace) used to pray while they were walking."