The World Federation One Stop Fiqh

Ruling 1345

A traveller who knows that he must perform qaṣr prayers but does not know some of its details – for example, he does not know that qaṣr prayers must be performed on an eight farsakh journey – then, in the event that he performs tamām prayers and realises this within the prescribed time for the prayer, he must, based on obligatory precaution, perform it again; and if he does not perform it again, he must make it up. However, if he realises after the time has expired, then there is no obligation to make it up.