Canto 3 -
Araṇya-kāṇḍa
Chapter 36: Rāvaṇa Requests Mārīca to Help him
Text 3.36.21
ततः पश्चात्सुखं रामे भार्याहरणकर्शिते।
विस्रब्धः प्रहरिष्यामि कृतार्थेनान्तरात्मना॥
tataḥ paścāt sukhaṁ rāme bhāryā-haraṇa-karśite
visrabdhaḥ prahariṣyāmi kṛtārthenāntar-ātmanā
tataḥ paścāt = and then; sukham = and happily; rāme = when Rāma; bhāryā-haraṇa-karśite = is emaciated because His wife is kidnapped; visrabdhaḥ = fearlessly; prahariṣyāmi = I will strike [at Him]; kṛta-arthena = with satisfied; antar-ātmanā = mind.
And then, when Rāma is emaciated because His wife is kidnapped, I will fearlessly and happily strike [at Him] with a satisfied mind.
Antar-ātmanā indicates that [Rāvaṇa thinks that] he would be internally firm [in purpose].