Hadith 2:605
Nafi said:
Ibn ‘Umar saw a man resting on his left hand while he was sitting during prayer. The version of Harun b. Zaid goes: He was lying on his left side. the agreed version goes: he said to him: Do not sit like this, because those who are punished sit like this.
حَدَّثَنَا هَارُونُ بْنُ زَيْدِ بْنِ أَبِي الزَّرْقَاءِ، حَدَّثَنَا أَبِي ح، وَحَدَّثَنَا مُحَمَّدُ بْنُ سَلَمَةَ، حَدَّثَنَا ابْنُ وَهْبٍ، - وَهَذَا لَفْظُهُ - جَمِيعًا عَنْ هِشَامِ بْنِ سَعْدٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّهُ رَأَى رَجُلاً يَتَّكِئُ عَلَى يَدِهِ الْيُسْرَى وَهُوَ قَاعِدٌ فِي الصَّلاَةِ - وَقَالَ هَارُونُ بْنُ زَيْدٍ سَاقِطًا عَلَى شِقِّهِ الأَيْسَرِ ثُمَّ اتَّفَقَا - فَقَالَ لَهُ لاَ تَجْلِسْ هَكَذَا فَإِنَّ هَكَذَا يَجْلِسُ الَّذِينَ يُعَذَّبُونَ
Original Reference: Sunan Abi Dawud 994