Sunan Abi Dawud, Hadith 889 ⓘ
Narrated Abdullah ibn Abbas: Ibn Abbas reported the Prophet as saying: I have been commanded - according to the version of Hammad: Your Prophet was commanded - to prostrate on seven (bones), and not to fold back the hair or the clothing.
حَدَّثَنَا مُسَدَّدٌ، وَسُلَيْمَانُ بْنُ حَرْبٍ، قَالاَ حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ طَاوُسٍ، عَنِ ابْنِ عَبَّاسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " أُمِرْتُ " . قَالَ حَمَّادٌ أُمِرَ نَبِيُّكُمْ صلى الله عليه وسلم - أَنْ يَسْجُدَ عَلَى سَبْعَةٍ وَلاَ يَكُفَّ شَعْرًا وَلاَ ثَوْبًا .
also referenced under: Hadith 888 (Hasan) & Book 3, Hadith 888 (USC-MSA)