Answered by Shaykh Faraz Rabbani
What happens if in the first sitting of a 4 rak’ah prayer, I read past the tashahhud, i.e.. the salawat and then realise I was supposed to stand….do I perform sajda sahw at the end?
Walaikum assalam wa rahmatullah,
If you unduly delay standing up after completing the first sitting of prayerby reciting beyond “Allahumma salli `ala Muhammadin wa `ala Aali Muhammad”then you left a necessary (wajib) element of prayer.
This follows the fiqh of forgetfulness: within prayer, it was necessary for you to have performed forgetfulness prostrations if done forgetfully. If unperformed, or if you did this action on purpose, then it would be necessary to repeat the prayer.
However, for numerous past errors–not current or a few past ones–one may follow the position that once the time is over it is sufficient to merely repent if one left necessary (wajib) actions of prayer. See answer(s) below.
Note that this does not apply to leaving obligatory (fard) actions: if these are left, the prayer is invalid. There is absolute scholarly consensus (ijma`) that invalid or missed prayers must be made up; any opinion to the contrary is a contravention of scholarly consensus and is thus considered aberrant (shadhdh). [Nawawi, al-Majmu`]
Wassalam,
The Rulings of the Sacred Law
Can I skip making up missed prayers by taking a [non-existent] Hanbali dispensation’?
Nawawi on making up missed prayers: scholarly consensus