question #3 Sahih al-Bukhari 860, Book 10, Hadith 251 : What does the arrangement of prayer rows in this narration indicate about the organization of prayer in Islam?

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.