Canto 3 -
Araṇya-kāṇḍa
Chapter 31: Rāvaṇa’s Conversation with Akampana and Mārīca
Text 3.31.28

न तं वध्यमहं मन्ये सर्वैर्देवासुरैरपि।
अयं तस्य वधोपायस्तं ममैकमनाः शृणु॥

na taṁ vadhyam ahaṁ manye sarvair devāsurair api
ayaṁ tasya vadhopāyas taṁ mamaika-manāḥ śṛṇu

na = not; tam = that He; vadhyam = is capable of being killed; aham = I; manye = think; sarvaiḥ deva-asuraiḥ = by all the devas and asuras [put together]; api = even; ayam = this; tasya vadha-upāyaḥ = is the means to kill Him; tam = of it; mama = from me; eka-manāḥ = with an attentive mind; śṛṇu = hear.

I think that He is not capable of being killed even by all the devas and asuras [put together]. This is the means to kill Him. With an attentive mind, hear of it from me.

GLOSS. The expression “by all the devas and asuras [put together]” is proper because at the time of the churning of the [milk] ocean, the devas and asuras were seen to be on friendly terms and hence their animosity was not constant.1

1 It is possible for the devas and asuras to set aside any mutual animosity to work together for a common goal. Akampana considered this possibility while speaking this verse and yet he recognized that Lord Rāma could not be killed by the combined endeavors of the devas and asuras.