Sahih Bukhari, Chapter: Virtues of the Prayer Hall (Sutra of the Musalla)

The things which annul the prayers were mentioned before me. They said, "Prayer is annulled by a dog, a donkey and a woman (if they pass in front of the praying people)." I said, "You have made us (i.e. women) dogs. I saw the Prophet praying while I used to lie in my bed between him and the Qibla. Whenever I was in need of something, I would slip away. for I disliked to face him."