Musnad Abu Ya'la al-Mawsili 51:2

Narrated to us Muhriz ibn 'Awn, narrated to us Khalaf ibn Khalifah, from al-Walid ibn Sari', the freed slave of the family of 'Amr ibn Hurayth, from 'Amr ibn Hurayth, who said: I prayed the dawn prayer behind the Prophet, may Allah bless him and grant him peace, and I heard him reciting: "Nay, I swear by the retreating stars, those that run and hide" (Surah at-Takwir). He said: And not one of us would bend his back until he [the Prophet] had straightened up in prostration.