Prayer: Definition of the Permitted Limit
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1304
The permitted limit is the place where the people of a town – including those who live on its outskirts and are considered residents of the town – cannot see a traveller due to the distance he has travelled. A traveller would know he has reached this point when he can no longer see the people of the town nor those living on its outskirts.