What is the ruling on changing the intention during prayer, for example: I forgot the Zuhr prayer, then I attended the 'Asr prayer and joined in the 'Asr prayer?

The questioner : He says: O honorable Shaykh, what is the ruling on changing the intention during prayer? For example: I forgot the Zuhr prayer, then I attended the 'Asr prayer and joined in the 'Asr prayer intending it to be 'Asr, then in the third rak'ah I remembered that I had not prayed Zuhr, so I changed the intention. What is required of me?

The Shaykh : All right. Now I ask you: when he changed the intention—from 'Asr to Zuhr—did he invalidate the 'Asr prayer or not? Did he invalidate the 'Asr prayer? He invalidated it. All right. He invalidated it. So the 'Asr prayer is invalid. And when he intended it to be Zuhr, was his intention valid when he had not intended it from the beginning? No. So both prayers are invalid. Therefore, he must repeat the Zuhr prayer and he must repeat the 'Asr prayer. And in a case like this, meaning, if a person had the Zuhr prayer due on him, and he entered into 'Asr while forgetting, and he remembered during the prayer, we say: Continue in your prayer as? 'Asr. And when you finish, pray the Zuhr prayer. The order is excused here because you were forgetting. And Allah the Exalted said: . But if you started a voluntary prayer and then remembered that you have an obligatory prayer due, cut off the voluntary prayer, cut it off, and enter into the obligatory prayer from the beginning. Yes.