Is it established that the Prophet (peace be upon him) combined two prayers without an excuse?

It is authentically reported from the Prophet (peace be upon him) that he combined the Dhuhr and Asr prayers, and the Maghrib and Isha prayers in Medina, without fear or rain, so as not to burden his Ummah. Scholars have differed in interpreting this hadith. Most of them have taken a position contrary to its apparent meaning, interpreting the combining therein as a "figurative combining" (jama' suri). Others, however, have held the view that it is permissible to combine prayers out of necessity for someone who does not make it a regular habit.