The ruling on intentionally omitting the prostration for forgetfulness before the closing salam

The questioner:
Honorable Shaykh, may Allah grant you success. The school of jurisprudence holds that intentionally omitting the prostration for forgetfulness, whose place is before the closing salam, invalidates the prayer, although the scholars differ on the circumstances in which the place of the prostration is determined.

The Shaykh:
We follow the school of jurisprudence.

The questioner:
The school of jurisprudence holds that intentionally omitting the prostration for forgetfulness, whose place is before the closing salam, invalidates the prayer,

The Shaykh:
Where did you take this from? Show us the source from which the school of jurisprudence took this. It is well known that the prostration for forgetfulness is permissible both before and after the closing salam, but it is better to do it before the closing salam if the omission was due to a deficiency, and after the closing salam if it was due to an addition. This is what we know from the school of jurisprudence.