Question Summary:
Is this an authentic practice?

Question Detail:

I read in a duaa book that if one does 2 sajdas after witr salah and In each sajda reads 5 times 'Subbuhun quddusun rabul malaaikata warrooh' and between the 2 sajdas reads ayatul kursi. Then his sins will be forgiven before he gets up. He gets the reward of 100 ummra and hajjs and gets the reward of shaheeds. Also 1000 angles right reward for him. He also gets the reward of freeing 100 slaves. He will also be able to on qiyamat intercede for 60 people doomed to hell. And he will also get the ability to die as a shaheed. I wanted to know if that is authentic or its just made up.

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The practice in reference is not found in the authentic books of hadith and fiqh.[1] 
And Allah Ta’āla Knows Best
Abdullah ibn Mohammed Aijaz
Student Darul Iftaa
Baltimore, USA 
Checked and Approved by,
Mufti Ebrahim Desai.