Abu Salamah narrates: Sayyiduna Mu'ayqib bin Abi Fatimah (may Allah be pleased with him) narrated to me that the Messenger of Allah (peace and blessings be upon him) said to a man who used to level the dust at the place of his prostration: "If it is necessary, doing it once is permissible."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3547