If the imam stands up for the third rak'ah in a four-rak'ah prayer and, while standing, remembers that it was a sitting, is it permissible for him to go back and sit?

The questioner : If the imam stands up for the third rak'ah in a four-rak'ah prayer and, while standing, remembers that it was a sitting, is it permissible for him to go back and sit?

The Shaykh : Do you remember that he had a sitting for the tashahhud?

The questioner : Yes, exactly.

The Shaykh : This matter has a detailed ruling in the Sunnah.

The questioner: Yes.

The Shaykh : If he has fully established himself in standing, he is not allowed to return to the tashahhud. However, if he has not fully established himself in standing, he must return to the tashahhud. In the first case, where we said he is not allowed to return, he must perform the prostration for forgetfulness. In the other case, where he must return to the tashahhud, he does not have to perform the prostration for forgetfulness. The hadith is explicit in this: if he has fully established himself in standing, he stands up and continues, for example, if he has not yet completed five [units of prayer] and is straightening up.

The questioner : If he is closer to standing up, meaning...

The Shaykh : Yes?

The questioner : If he is closer to standing up.

The Shaykh : This is a philosophical matter; perhaps we should not discuss it. Whether he has fully established himself in standing or not, what does "closer to standing up" mean?

The questioner : He has not fully established himself in standing.

The Shaykh : He has not fully established himself in standing. If he raises his head from the tashahhud, from the second prostration, and so on, and he is thinking, having fully established himself in standing, he is not allowed to return. But if he is thinking, and there is only a little left, and he remembers, so he returns, then if he returns and has not fully established himself in standing, he has done well and does not have to perform the prostration for forgetfulness. However, if he has fully established himself in standing, it is not only that he does not have to return to the tashahhud, but it is not permissible for him to return. If he does so, he has done wrong. And if he has done wrong, he must perform the prostration for forgetfulness in this case. But the difference between the case where he has not fully established himself and returns, in which he is on the right path, and the case where he has fully established himself and returns, in which he is contrary to the Shari'ah, is that this is a violation which, in my view, a Muslim would not intend. Because a Muslim’s custom is to intend a violation only in something where he has a personal interest, and this is where sins come from, or this is the reason people fall into sins, because they find pleasure in them. Here, there is nothing of the sort. Here, he returns, makes an effort, performs the tashahhud, and sins by violating the Shari'ah. So it is not conceivable that a Muslim would intentionally oppose the Shari'ah. But it is either due to forgetfulness or a slip of the tongue. Sometimes a person is surprised by things he cannot control, and he does not act with wise, Shari'ah-compliant behavior, so he falls into this error. He may have straightened up in standing, and someone might say, "Subhan Allah," and he goes back to the tashahhud. This is an error. But it is not permissible if he remembers to do so. All right.