Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 19: Viśvāmitra Requests Daśaratha to Give Rāma
Text 1.19.12

वीर्योत्सिक्तौ हि तौ पापौ कालपाशवशं गतौ।
रामस्य राजशार्दूल न पर्याप्तौ महात्मनः।
न च पुत्रकृतस्नेहं कर्तुमर्हसि पार्थिव॥

vīryotsiktau hi tau pāpau kāla-pāśa-vaśaṁ gatau
rāmasya
rāja-śārdūla na paryāptau mahātmanaḥ
na
ca putra-kṛta-snehaṁ kartum arhasi pārthiva

vīrya utsiktau hi = proud of their prowess; tau = those two; pāpau = sinful rākṣasas; kāla-pāśa-vaśam = under the control of Yamarāja; gatau = have come; rāmasya = Rāma; rāja-śārdūla = O tiger among kings; na = no; paryāptau = match they are; mahā-ātmanaḥ = for the great soul; na ca = not; putra-kṛta-sneham = by affection considering Him to be your son; kartum arhasi = you should be overcome; pārthiva = O king.

Proud of their prowess, those two sinful rākṣasas have come under the control of Yamarāja. O tiger among kings, they are no match for the great soul Rāma. O king, you should not be overcome by affection, considering Him to be your son.

Still, how is it possible for them to be conquered over if they are greatly powerful? That is answered here. Due to their sins, they are now nearing their death.