When all the deities spoke to Brahma thus, he thought for a while and then said "Aha! The idea to kill that evil-minded Ravana is discerned." [1-15-12]
तेन गन्धर्वयक्षाणां देवतानां च रक्षसाम् | अवध्योऽस्मीति वागुक्ता तथेक्तं च तन्मया || १-१५-१३
"Ravana said while seeking boon that, 'I shall not be killed by gandharva-s, yaksha-s, or by gods, or by other demons...' and I also said 'so be it..." [1-15-13]
नाकीर्तयदवज्ञानात्तद्रक्षो मानुषांस्तदा | तस्मात् स मानुषाद्वध्यो मृत्युर्नान्योऽस्य विद्यते || १-१५-१४
"That demon did not express about humans then with his disrespect to them, and evidently his death does not occur otherwise." So said Brahma to gods. [1-15-14]