Sayyiduna Anas (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) used to offer prayer on a mat. In one narration the words are: He used to prostrate on it.
Tabarani recorded it in al-Mu'jam al-Awsat and al-Mu'jam al-Saghir with chains, one of which has narrators who are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2269