Prayer: First Condition for Shortened (Qasr) Prayers: Distance
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1258
If the following eight conditions are fulfilled, a traveller must perform ẓuhr, ʿaṣr, and ʿishāʾ prayers in their shortened (qaṣr) form; i.e. he must perform them as two rakʿah prayers.
First condition: the journey must not be less than eight farsakhs (approximately forty-four kilometres) [which is equal to approximately twenty-seven and a half miles].
If a person’s outward and return journey totals eight farsakhs – irrespective of whether or not the outward or the return journey on its own is less than four farsakhs – he must perform qaṣr prayers. Therefore, if his outward journey is three farsakhs and his return is five, or vice versa, he must perform qaṣr prayers, i.e. [he must perform the four rakʿah prayers] as two rakʿah prayers.