Question Summary:
Is it permissible to continue Salaah after one thinks it is over and engages in dua.

Question Detail:

If a masbooq makes both salams with imam raises both hands for dua and realises mistake and completes rakah and sahw,will salah be ok or repeat

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
In principle, if one does salaam, whether behind an imam or individually, and then realises that he still has some rakaa’ats to complete, he can stand up and complete those missed rakaa’ats and make sajdah al-sahw, as long as he didn’t turn away from the qiblah or do anything that breaks the salaat.[1]
In the case in reference, the salaat will be valid and does not have to be repeated. [2]
And Allah Ta’āla Knows Best
Muhammad Haris Siddiqui
Student Darul Iftaa
Melbourne, Australia  
Checked and Approved by,
Mufti Ebrahim Desai.