صَحِيحُ مُسْلِمٍ
Sahih Muslim 546 a
The Book of Mosques and Places of Prayer
It is disliked to smooth the pebbles or make the dirt level during salat
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا هِشَامٌ الدَّسْتَوَائِيُّ، عَنْ يَحْيَى بْنِ أَبِي كَثِيرٍ، عَنْ أَبِي سَلَمَةَ، عَنْ مُعَيْقِيبٍ، قَالَ ذَكَرَ النَّبِيُّ صلى الله عليه وسلم الْمَسْحَ فِي الْمَسْجِدِ - يَعْنِي الْحَصَى - قَالَ إِنْ كُنْتَ لاَ بُدَّ فَاعِلاً فَوَاحِدَةً .
Mu'aiqib quoted the Messenger of Allah (ﷺ) mentioning the removal of pebbles from the ground where he prostrated himself. He (the Prophet) said: It you must do so, do it only once.
Sahih Muslim, 546 aSahihصحيح