Hadith 503930
Chapter 9: Shortening the Prayer - كتاب قصر الصلاة فى السفر
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ إِذَا سَجَدَ وَضَعَ كَفَّيْهِ عَلَى الَّذِي يَضَعُ عَلَيْهِ جَبْهَتَهُ . قَالَ نَافِعٌ وَلَقَدْ رَأَيْتُهُ فِي يَوْمٍ شَدِيدِ الْبَرْدِ وَإِنَّهُ لَيُخْرِجُ كَفَّيْهِ مِنْ تَحْتِ بُرْنُسٍ لَهُ حَتَّى يَضَعَهُمَا عَلَى الْحَصْبَاءِ .
Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to place his palms flat on the surface where he put his forehead. Nafi said, "I have seen him take his hands out from under his burnus on a very cold day and place them on the ground."
Reference Muwatta Malik 503930
USC-MSA web (English) reference : Book 9, Hadith 62