Sahih al-Bukhari 860
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · The ablution for boys (youngsters). When they should perform Ghusl (take a bath) and Tuhur (purification). Their attendance at congregational prayers and their rows in the prayers.
Narrated Anas bin Malik:
حَدَّثَنَا إِسْمَاعِيلُ ، قَالَ حَدَّثَنِي مَالِكٌ ، عَنْ إِسْحَاقَ بْنِ عَبْدِ اللَّهِ بْنِ أَبِي طَلْحَةَ ، عَنْ أَنَسِ بْنِ مَالِكٍ ، أَنَّ جَدَّتَهُ، مُلَيْكَةَ دَعَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم لِطَعَامٍ صَنَعَتْهُ، فَأَكَلَ مِنْهُ فَقَالَ " قُومُوا فَلأُصَلِّيَ بِكُمْ ". فَقُمْتُ إِلَى حَصِيرٍ لَنَا قَدِ اسْوَدَّ مِنْ طُولِ مَا لُبِسَ، فَنَضَحْتُهُ بِمَاءٍ فَقَامَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَالْيَتِيمُ مَعِي، وَالْعَجُوزُ مِنْ وَرَائِنَا، فَصَلَّى بِنَا رَكْعَتَيْنِ.
My grandmother Mulaika invited Allah's Messenger (ﷺ) for a meal which she had prepared specially for him. He ate some of it and said, "Get up. I shall lead you in the prayer." I brought a mat that had become black owing to excessive use and I sprinkled water on it. Allah's Messenger (ﷺ) stood on it and prayed two rak`at; and the orphan was with me (in the first row), and the old lady stood behind us.