It is narrated from Anas bin Malik (may Allah be pleased with him) that his grandmother, Malikah (may Allah be pleased with her), invited the Messenger of Allah (ﷺ) for a meal which she had prepared as a treat for him. The Prophet (ﷺ) ate the food, then said: "Come, let me lead you in prayer." Anas (may Allah be pleased with him) said: I stood towards a mat which had turned black due to frequent use in our house. I sprinkled water on it to clean it, then the Messenger of Allah (ﷺ) stood on it. I and a small boy formed a row behind him, and the old woman stood behind us. The Prophet (ﷺ) led us in two rak‘ahs of prayer, then departed.
Hadith Referenceمسند الإمام الشافعي / كتاب الصلاة / 287
Hadith Takhrijاخرجہ البخاری، الصلاة، باب الصلاة علی الحصیر: 380، ومسلم، المساجد، باب جواز الجماعة فی النافلة، والصلاة علی حصیر وخمرة وثوب وغیرہا من الطاہرات: 658۔