Prayer: Covering for Forgotten Acts and Sajdata al-Sahw
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 777
When someone makes up a forgotten sajdah or tashahhud, he must cover himself in the same manner as when he performs prayers. And the recommended precaution is that he should cover himself in this manner when he performs sajdatā al‑sahw as well.