The Book of Mosques and Places of Prayer
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
From Sahih Muslim, whose reports the scholars accept as authentic.