Sahih Muslim Book - 4, Hadith - 1095

وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى وَأَبُو الرَّبِيعِ الزَّهْرَانِىُّ قَالَ يَحْيَى أَخْبَرَنَا وَقَالَ أَبُو الرَّبِيعِ حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ عَنْ عَمْرِو بْنِ دِينَارٍ عَنْ طَاوُسٍ عَنِ ابْنِ عَبَّاسٍ قَالَ أُمِرَ النَّبِىُّ -صلى الله عليه وسلم- أَنْ يَسْجُدَ عَلَى سَبْعَةٍ وَنُهِىَ أَنْ يَكُفَّ شَعْرَهُ وَثِيَابَهُ. هَذَا حَدِيثُ يَحْيَى. وَقَالَ أَبُو الرَّبِيعِ عَلَى سَبْعَةِ أَعْظُمٍ وَنُهِىَ أَنْ يَكُفَّ شَعْرَهُ وَثِيَابَهُ الْكَفَّيْنِ وَالرُّكْبَتَيْنِ وَالْقَدَمَيْنِ وَالْجَبْهَةِ.

It was narrated that Ibn 'Abbas said: "The Prophet (s.a.w) ordered that we should prostrate on seven bones, and he forbade tucking up one's hair and garment." This is the Hadith of Yahya. Abu Ar-Rabi' (in his narration) said: "... on seven bones, and it was forbidden to tuck up one's hair or garment: The (bones are of) the hands, the knees, the feet, and the forehead."