سُنَنُ أَبِي دَاوُدَ
Sunan Abi Dawud 962
Prayer (Kitab Al-Salat)
How Should One Sit In The Tashah-hud
حَدَّثَنَا هَنَّادُ بْنُ السَّرِيِّ، عَنْ وَكِيعٍ، عَنْ سُفْيَانَ، عَنِ الزُّبَيْرِ بْنِ عَدِيٍّ، عَنْ إِبْرَاهِيمَ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا جَلَسَ فِي الصَّلاَةِ افْتَرَشَ رِجْلَهُ الْيُسْرَى حَتَّى اسْوَدَّ ظَهْرُ قَدَمِهِ .
It was reported from Ibrahim that he said: "When the Prophet (ﷺ) would sit in the prayer, he would place his left foot horizontally - so much so that the upper-part of his foot became black."
Sunan Abi Dawud, 962Da'if (Al-Albani)ضعيف (الألباني)