(157) باب أَعْضَاءِ السُّجُودِ
Narrated Abdullah ibn Abbas:
Ibn Abbas reported the Prophet (ﷺ) as saying: I have been commanded - according to the version of Hammad: Your Prophet (ﷺ) was commanded - to prostrate on seven (bones), and not to fold back the hair or the clothing.
Reference: Sunan Abi Dawud 889
In-book reference: Book 2, Hadith 499
English translation: Book 3, Hadith 888