Imâm Sâlih bin Fawzân al-Fawzân
Question: Is it allowed to do Sujood ash-Shukr (The Prostration of Thankfulness) while performing the obligatory prayers?
Answer: No. Sujood ash-Shukr during the obligatory prayers would invalidate that prayer. The same applies to voluntary prayers, because that would be an addition in a prayer.