A man joined the imam for the 'Asr prayer, then remembered that he had not prayed the Zuhr prayer, so he changed his intention to Zuhr. Is it valid?

The questioner:
Yes. Peace be upon you. May Allah keep you in good health, Shaykh 'Abd al-'Aziz. Shaykh, if I joined the imam for the 'Asr prayer and then remembered that I had not prayed the Zuhr prayer, may I change my intention to Zuhr?

The Shaykh:
Break it off, and say the takbir of ihram for the Zuhr prayer.

The questioner:
Meaning, it is necessary.

The Shaykh:
Then pray the 'Asr prayer after that.

The questioner:
Meaning, I am required to break it off, and changing the intention is not sufficient. What if I only changed the intention and did not break it off?

The Shaykh:
You have broken the intention, and you have missed one or two rak'ahs, which you make up after the taslim.

The questioner:
It happened now, Shaykh, that I changed the intention, Shaykh.

The Shaykh:
Sa'y.

The questioner:
This is a repetition.

The Shaykh:
You pray the Maghrib prayer, then you repeat the 'Asr prayer.

The questioner:
Do I pray what? The Zuhr? Yes.

The Shaykh:
Then he prayed.