This was declared by the Rakshasa as the Mantra that should be used as a remedy for curing a person possessed by a Rakshasa or one killed by poison.
इति रक्षोपसृष्टेषु विषवीर्यहतेषु च। राक्षसं भैषजं प्रोक्तं संसिद्धवचनोत्तरम्॥