What is the ruling on a person praying alone who recited the tashahhud instead of the Fatiha?

The questioner : Shaykh, a man was standing in place of the Fatiha and recited the tashahhud. He did not remember until he was prostrating. What is his obligation? Is his prayer valid?

The Shaykh : Remember what?

The questioner : He remembered that he recited the tashahhud while standing in place of the tahiyyat, instead of the Fatiha, for example.

The Shaykh : Meaning he did not recite the Fatiha?

The questioner: No.

The Shaykh : In which rak'ah?

The questioner : In the first rak'ah...

The Shaykh : Yes.

The questioner : In the first rak'ah.

The Shaykh : Is it a silent prayer or a loud prayer?

The questioner : A company.

The Shaykh : In a loud prayer, the imam bears it for him. In a loud prayer, it is not permissible for him to recite.

The questioner : He is alone, praying individually, not a ma'mum.

The Shaykh : Ah, an individual.

The questioner: Yes.

The Shaykh : Ah, he must repeat the rak'ah.

The questioner : And if he was a ma'mum.

The Shaykh : The imam bears it.

The questioner : Glory be to Allah, meaning it is not a pillar.

The Shaykh : The imam bears it.

The questioner : Even if it were a pillar.

The Shaykh: Yes.

The questioner : What Allah wills, Allah is the Greatest!