Confirmed Sunnahs of the Prophet.
Praying facing a barrier (sutrah).
On the authority of Musa ibn Talha, on the authority of his father, who said:
The Messenger of Allah, peace and blessings of Allah be upon him, said:
"When one of you places before himself the likes of the rear wooden peg of a camel saddle,
let him pray and pay no mind to whoever passes beyond that."
A sutrah is whatever a worshipper places in front of himself during prayer,
such as a wall, a pillar, or anything similar.
The rear peg of a camel saddle
is approximately two-thirds of a cubit in height.