Sunan Abi Dawud 21405
In-book no 901حَدَّثَنَا عَبْدُ الْمَلِكِ بْنُ شُعَيْبِ بْنِ اللَّيْثِ، حَدَّثَنَا ابْنُ وَهْبٍ، حَدَّثَنَا اللَّيْثُ، عَنْ دَرَّاجٍ، عَنِ ابْنِ حُجَيْرَةَ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " إِذَا سَجَدَ أَحَدُكُمْ فَلاَ يَفْتَرِشْ يَدَيْهِ افْتِرَاشَ الْكَلْبِ وَلْيَضُمَّ فَخِذَيْهِ " .
Abu Hurairah reported the Prophet(ﷺ) as saying: when one of you prostrates himself, he should not stretch out his forearms( on the ground) like a dog and he should join both of his thighs.