If a traveller who has made the intention to stay somewhere for ten days keeps a fast and after the time for ẓuhr prayers he changes his mind about staying there, in the event that he has performed a four rakʿah prayer within its prescribed time, the fasts he keeps there are valid and he must perform tamām prayers. However, if he has not performed a four rakʿah prayer within its prescribed time, he must, as an obligatory precaution, complete that day’s fast and make it up as well.
Furthermore, he must also perform qaṣr prayers and he cannot fast on the remaining days.