Virtues of the Prayer Hall (Sutra of the Musalla)
Bukhari :: Book 1 :: Volume 9 :: Hadith 478
Narrated 'Aun bin Abi Juhaifa:
that he had heard his father saying, "Allah's Apostle came to us at mid-day and water was brought for his ablution. He performed ablution and led us in Zuhr and 'Asr prayers with an 'Anza planted in front of him (as a Sutra), while women and donkeys were passing beyond it."