What is the distance and duration for which shortening the prayer is permissible?

Question:
May Allah reward you with good, and may He do you good. Our brother asks: What is the distance at which a man becomes a traveler, and thus shortens the prayer? And how many days may he shorten the prayer if he stays in one city for a number of days, for example?

Answer:
As for the distance, the scholars have differed on the amount of distance for which the prayer is shortened. The most likely view, and Allah knows best, is a two-day journey for a mount, a two-day journey for a mount by the pace of the feet and the movement of heavy loads, as the jurists say. Its measure in the known kilometers today is approximately eighty kilometers. This is the amount of distance considered the distance for shortening. As for if the traveler stays during his journey intending to remain for more than four days, then it is obligatory for him to complete the prayer, because the rulings of travel have been severed for him. But if he intends to stay for four days or less, then he continues to shorten, because the rulings of travel have not been severed for him. Likewise, if he stays for a duration he does not know when it will end, and he has not specified it, then the rulings of travel are also not severed for him; rather, he continues to shorten if he prays alone or with a group of travelers. But if he prays with an imam who completes the prayer, then he is required to complete it in all cases.