Prayer: Travelling Without Knowing the Distance of the Journey
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1267
With regard to someone who does not know how many farsakhs his journey is – for example, he travels to find a lost person and does not know how far he must go before he finds him – he must perform tamām prayers. However, on the return journey, in the event that the distance to his home town or to a place where he intends to stay for ten days is eight or more farsakhs, he must perform qaṣr prayers. Similarly, if during his journey he makes an intention to travel a distance that together with the return journey totals eight farsakhs, he must perform qaṣr prayers.