Ruling 1309 — Prayer (Ṣalāh)

If a person is certain that he has reached the permitted limit and performs his prayer in qaṣr form, and later he realises that when he performed his prayer he had not actually reached the permitted limit, he must perform the prayer again. When he performs the prayer again, if he has still not reached the permitted limit, he must perform the prayer in tamām form, but if he has passed it, he must perform it in qaṣr form. If the time for the prayer has expired, he must perform it according to what his duty was when the prescribed time for it expired.