Sunan Ibn Majah, Volume 2, Book 5, Hadith 885 (DarusSalam) ⓘ
It was narrated from ‘Abbas bin ‘Abdul-Muttalib that he heard the Prophet say: “When a person prostrates, seven parts of his body prostrate with him: His face, his two hands, his two knees, and his two feet.”
حَدَّثَنَا يَعْقُوبُ بْنُ حُمَيْدِ بْنِ كَاسِبٍ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ أَبِي حَازِمٍ، عَنْ يَزِيدَ بْنِ الْهَادِ، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ التَّيْمِيِّ، عَنْ عَامِرِ بْنِ سَعْدٍ، عَنِ الْعَبَّاسِ بْنِ عَبْدِ الْمُطَّلِبِ، أَنَّهُ سَمِعَ النَّبِيَّ ـ صلى الله عليه وسلم ـ يَقُولُ " إِذَا سَجَدَ الْعَبْدُ سَجَدَ مَعَهُ سَبْعَةُ آرَابٍ وَجْهُهُ وَكَفَّاهُ وَرُكْبَتَاهُ وَقَدَمَاهُ " .
also referenced under: Hadith 885 (Reference) & Book 5, Hadith 935 (In-Book)