Question: If a person is praying the Isha prayer and while he still has plenty of time to pray the Isha prayer, in the second rakat something urgent happens to him, can he change his intention (Niyyah) to the morning qadha prayer and complete his prayer in two rakats?
Answer: It is possible to change the intention of prayer from performing in-time (Ada’), to Qadha with two conditions:
1: The prayer time should not be tight
2: The prayer stage for changing the intention has not passed. (For example, you cannot change the intention to a two-Rakat prayer when you’ve bowed for the ruku’ of the third Rakat)