Is it permissible for a traveler to combine the Dhuhr and Asr prayers while separating them by half an hour or more, and what is the ruling for someone who intended to combine and prayed Dhuhr, then forgot and remembered after an hour or more?

The majority of jurists stipulated for the validity of Jam‘ at-Taqdim (combining two prayers by praying the second one early) that there should not be a long interval between the two prayers. If the interval is long, the combining becomes void, and the second prayer must be delayed until its prescribed time. Some Shafi’is and Ibn Taymiyyah are of the view that continuity between the two prayers is not a condition for combining, as long as the time of the first prayer has not expired. It is more cautious to adopt the opinion of the majority, but it is permissible to follow the other opinion by way of taqlid (following a qualified scholar).