Is it permissible to shorten and combine prayers while traveling by plane if the duration of stay in the destination country does not exceed two days? And does the ruling differ if this is the nature of the person's work?

Shortening and combining prayers for a traveler is correct and conforms to the guidance of the Prophet, peace and blessings be upon him, which he and his Caliphs consistently practiced. It is a concession that Allah loves to be utilized. However, if a traveler enters his homeland without intending to reside there, or enters a country where he has a wife with whom he has consummated marriage, or intends to reside for four days excluding the days of entry and and exit, then he must pray in full.