What is the distance for qasr (shortening prayers) when traveling, and can one shorten prayers after returning home for three days?

The majority of jurists hold that a traveler undertaking a permissible journey of four burd (plural of burdah) is recommended to shorten the four-rak'ah prayer to two rak'ahs. This distance is approximately 83 kilometers. The ruling of travel ends immediately upon returning to the country from which one departed, even if one has not yet reached home; in this case, one must complete the prayer obligatorily. Ibn Qudamah mentioned in Al-Mughni that Imam Ahmad stated the shortening of prayer applies to a distance of four burd, which is sixteen farsakh. In Al-Muhadhdhab (Shafi'i school), shortening is not permissible except for a journey of two days, meaning four burd (sixteen farsakh), citing the actions of Ibn Umar and Ibn Abbas, and that this distance involves repeated hardship of travel.