Does the imam who forgot and stood up for the third rak'ah without the tashahhud return to it?

The questioner : All right, our Shaykh, in the same question, regarding this fourth or fifth rak'ah, he stood up. He stood up in the third rak'ah and did not sit for the first tashahhud, so they alerted him. Should he sit down or remain standing?

The Shaykh : If he has fully established himself in a standing position, it is not permissible for him to return. If he has fully established himself in a standing position, the Hanafi school has a specific philosophy regarding this. They say that if he is closer to standing, it is not permissible, and if he is closer to sitting, he returns. This has no basis in the Sunnah. The Sunnah explicitly states that if he has fully established himself in a standing position, he remains standing and does not return. He must perform the prostration for forgetfulness. If he has not fully established himself in a standing position, he returns and performs the tashahhud, and the prostration for forgetfulness is not required of him. "Fully established in a standing position" is clear: a healthy young man with a sound build fully establishes himself in a standing position when he becomes vertical and upright. As for the one who is unable, who naturally, when he stands in prayer, stands in this manner, this is his full establishment. So everything is according to his condition; he may be young or he may be sick. If he has an illness in his back and cannot stand vertically like that, but with some leaning forward, this is called having fully established himself in a standing position, and so on.

The questioner : May Allah reward you with good.

The questioner : It is permissible for one to try cold and hot water while standing.

The Shaykh : It is permissible...