The Book of The At-Tatbiq (Clasping One's Hands Together)
12/48. Chapter:
Bending the toes (so that they point toward the Qiblah) during prostration
Sunan an-Nasai
أَخْبَرَنَا مُحَمَّدُ بْنُ بَشَّارٍ، قَالَ حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا عَبْدُ الْحَمِيدِ بْنُ جَعْفَرٍ، قَالَ حَدَّثَنِي مُحَمَّدُ بْنُ عَطَاءٍ، عَنْ أَبِي حُمَيْدٍ السَّاعِدِيِّ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا أَهْوَى إِلَى الأَرْضِ سَاجِدًا جَافَى عَضُدَيْهِ عَنْ إِبْطَيْهِ وَفَتَخَ أَصَابِعَ رِجْلَيْهِ . مُخْتَصَرٌ .
It was narrated that Abu Humaid As-Sa'idi said: "When the Prophet (ﷺ) fell to the ground during prostration, he held his arms away from his sides and bent his toes."
Reference : Sunan an-Nasa'i 1101In-book reference : Book 12, Hadith 73English translation : Vol. 2, Book 12, Hadith 1102