What is the ruling on combining and shortening prayers between their two times, such as performing the Dhuhr and Asr prayers at two o'clock after the Dhuhr time has ended and before the Asr time has begun?

There is no interval between the times for Dhuhr prayer and Asr prayer. As soon as the time for Dhuhr ends, the time for Asr begins immediately. Ibn Qudamah said: "In summary, the time for Asr is from the moment the shadow of an object becomes its equal plus even the slightest increase, immediately following the Dhuhr time, with no separation between them." Al-Nawawi said: "The time for Asr begins when the shadow of everything becomes its equal, which is when the Dhuhr time ends. There is no overlap between them, nor is there any interval."