Arabic (Original)
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ أَبُو أَحْمَدَ الزُّبَيْرِيُّ حَدَّثَنَا كَثِيرُ بْنُ زَيْدٍ عَنْ نَافِعٍ قَالَ كَانَ عَبْدُ اللَّهِ بْنُ عُمَرَ إِذَا جَلَسَ فِي الصَّلَاةِ وَضَعَ يَدَيْهِ عَلَى رُكْبَتَيْهِ وَأَشَارَ بِإِصْبَعِهِ وَأَتْبَعَهَا بَصَرَهُ ثُمَّ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَهِيَ أَشَدُّ عَلَى الشَّيْطَانِ مِنْ الْحَدِيدِ يَعْنِي السَّبَّابَةَ.
English Translation
Muhammad b. Abdullah Abu Ahmad al-Zubayri told us, Kathir b. Zayd told us, from Nafi', who said: Abdullah b. Umar, when he sat in the prayer, would place his hands on his knees, point with his finger, and follow it with his gaze, then say: The Messenger of Allah, peace and blessings be upon him, said: "It is harder on Satan than iron" - meaning the index finger.