Mistake in a Sunnatul Muakkadah Salaah
A person made a mistake in a Sunnatul Muakkadah salaah making sajda sahw necessary. However he forgot to make sajda sahw. Does he have to repeat the salaah? Is there a difference between repeating the salaah in the salaah time and out of the salaah time?
Assalāmuʿalaykum Wa Raḥmatullāhi Wa Barakātuh
If a person did not make Sajdah Sahw where necessary, then it will be Wājib (obligatory) upon him to repeat that Ṣalāh provided that the timeframe of that Ṣalāh has not lapsed.
If the time has expired, then he will not repeat that Ṣalāh.