Is it permissible to combine the Asr prayer with the Dhuhr prayer as an early combination (jam' taqdim), or with the Maghrib prayer as a delayed combination (jam' ta'khir), due to work and study and the inability to perform it at its designated time?

It is not permissible to combine the Asr prayer with the Maghrib prayer, according to the consensus of the Ummah; based on the statement of Ibn Qudamah: "There is no disagreement among the Ummah regarding the impermissibility of that." The Asr prayer must be performed within its prescribed time, even if it means stopping on the road or praying inside the car. If that is not possible, it is permissible to combine it with the Dhuhr prayer, provided that this is not made a regular habit. One must be careful not to neglect prayers, especially Asr, because it is "the middle prayer" as mentioned by Sheikh al-Islam.