The space between the place where the Messenger of Allah ﷺ prayed and the wall was just enough for a sheep to pass through.
كان بين مصلى رسول الله ﷺ وبين الجدار ممر الشاة.
Bukhari narrated it in the Book of Prayer (496), and Muslim narrated it in the Book of Prayer (508), both of them through the route of Abdul-Aziz bin Abu Hazim, from his father, from Sahl bin Saad Saadi, who mentioned it. In the wording of Abu Dawud (696), "Between the place where the Prophet ﷺ stood and the qibla there was space enough for a goat to pass."