Is it always obligatory to combine prayers with shortening them while traveling? Is shortening prayers obligatory due to the Prophet's constant practice of it during his travels? What is the ruling on combining and shortening prayers for a pilgrim from Makkah or elsewhere? What is the ruling on Uthman's prayer in Mina? Is it permissible for a student who travels daily for studies to shorten and combine prayers?

Combining prayers is not linked to shortening them. Shortening prayers is specific to travel, whereas combining them is permissible both during travel and at home if there is a reason for it. It is legislated for the pilgrim to combine Dhuhr and Asr prayers at Arafat as Jam' Taqdim (combining early), and Maghrib and Isha prayers at Muzdalifah as Jam' Ta'kheer (combining late), due to its establishment from the Prophet, peace and blessings be upon him. It is sunnah for the pilgrim who is not a resident of Mina to shorten prayers in Mina and during the days of Tashreeq, and this is the most preponderant opinion. Shortening prayers is a concession for the traveler, not an obligation. The Hadith from Al-Musnad that the questioner referred to is weak. It is permissible to shorten and combine prayers when traveling to Medina if the distance exceeds 83 km and there is no intention to reside there for more than four days.