Answered by: Mufti Mohammed Tosir Miah
Is it permissible to pray behind an Imam who prayed three rakats witr with one Salam but only had one tashahhud in the last Rakat?
In the name of Allah, the Most Gracious, the Most Merciful
A detailed answer has been given before regarding the issue of Witr Salah.
In the aforementioned scenario, the sitting after the second rakaat is obligatory. Hence, if someone missed it out and did not perform Sajdah Sahwe, such a Salah will be accepted, but without the full reward. (Mazahirul Haqq p.21 v.2)
Therefore, in the future, it is best that you do not pray behind someone who prays three rakaats in one sitting.
Only Allah Knows Best
Written by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham