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."  

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 say, "When one of you puts his forehead on the ground he should put his palms on the place where he puts his forehead. Then, when he rises, he should raise them, for the hands prostrate just as the face prostrates."  

أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ كَانَ يَقُولُ مَنْ وَضَعَ جَبْهَتَهُ بِالأَرْضِ فَلْيَضَعْ كَفَّيْهِ عَلَى الَّذِي يَضَعُ عَلَيْهِ جَبْهَتَهُ ثُمَّ إِذَا رَفَعَ فَلْيَرْفَعْهُمَا فَإِنَّ الْيَدَيْنِ تَسْجُدَانِ كَمَا يَسْجُدُ الْوَجْهُ