بُلُوغُ الْمَرَامِ
Bulugh al-Maram 297
The Book of Prayer
وَعَنْ اِبْنِ عَبَّاسٍ -رَضِيَ اَللَّهُ عَنْهُمَا- قَالَ: قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ أُمِرْتُ أَنْ أَسْجُدَ عَلَى سَبْعَةِ أَعْظُمٍ : عَلَى اَلْجَبْهَةِ - وَأَشَارَ بِيَدِهِ إِلَى أَنْفِهِ - وَالْيَدَيْنِ , وَالرُّكْبَتَيْنِ , وَأَطْرَافِ اَلْقَدَمَيْنِ } مُتَّفَقٌ عَلَيْهِ . [1]
Narrated Ibn 'Abbas (RA): Allah's Messenger (ﷺ) said: "I have been commanded to prostrate on seven bones; on the forehead - and he pointed at his nose, the hands (the palms), the knees and the tips (toes) of the feet." [Agreed upon].
Sunnah.com reference: Book 2, Hadith 183