Sayyiduna Imam al-Husayn bin Ali (may Allah be pleased with him) narrates: While performing ablution, the Prophet (peace and blessings be upon him) would wash the place of prostration with water, to the extent that he would pour water over the place of prostration.
Abu Ya'la recorded it, and its chain is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1191