It is narrated from Sayyiduna Mu'ayqib (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "If you must do it, then only once" - he said this regarding moving aside (levelling) the pebbles.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17949