The Book of Mosques and Places of Prayer
5/12. Chapter:
It is disliked to smooth the pebbles or make the dirt level during salat
Sahih Muslim
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.
Reference : Sahih Muslim 546aIn-book reference : Book 5, Hadith 59USC-MSA web (English) reference : Book 4, Hadith 1114