Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 29: The History of Siddhāśrama
Text 1.29.2

इह राम महाबाहो विष्णुर्देववरः प्रभुः।
वर्षाणि सुबहून्येव तथा युगशतानि च।
तपश्चरणयोगार्थमुवास सुमहातपाः॥

iha rāma mahā-bāho viṣṇur deva-varaḥ prabhuḥ
varṣāṇi
subahūny eva tathā yuga-śatāni ca
tapaś-caraṇa-yogārtham
uvāsa su-mahātapāḥ

iha = here; rāma = Rāma; mahā-bāhuḥ = O great-armed; viṣṇuḥ = Viṣṇu; deva-varaḥ = the excellent Lord; prabhuḥ = and master; varṣāṇi = years; subahūni eva = for many, many; tathā yuga-śatāni ca = and hundreds of millenia; tapaḥ-caraṇa-yoga-artham = to attain the perfection of those austerities and meditation; uvāsa = resided; su-maha-tapāḥ = performing extremely great austerities.

O great-armed Rāma, the excellent Lord and master Viṣṇu resided here performing extremely great austerities to attain the perfection of performing austerities and meditation for many, many years and hundreds of millenia.

NOTE. Between the first and second lines of this text, the following verse is additionally found in some readings of the Rāmāyaṇa:

pradṛśyaḥ sarva-bhūtānāṁ sarvātmā sarva-lokabhṛt
mohanārthaṁ
tu lokasya sarveṣāṁ jagatāṁ prabhuḥ

“Making Himself visible to all creatures, the soul of all, the maintainer of everyone and the master of all worlds, [performed such austerities] to bewilder the common man.”