Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 29: The History of Siddhāśrama
Text 1.29.36

तेनैष पूर्वमाक्रान्त आश्रमः श्रमनाशनः।
मया तु भक्त्या तस्यैष वामनस्योपभुज्यते॥

tenaiṣa pūrvam ākrānta āśramaḥ śrama-nāśanaḥ
mayā
tu bhaktyā tasyaiṣa vāmanasyopabhujyate

tena = by Him; eṣaḥ = this; pūrvam = in the past; ākrāntaḥ = was taken over; āśramaḥ = āśrama; śrama-nāśanaḥ = that removes the fatigue of material existence; mayā tu = I; bhaktyā = out of devotion; tasya = for; Him eṣaḥ = this āśrama; vāmanasya = of Vāmana; upabhujyate = have taken shelter of.

This āśrama that removes the fatigue of material existence was taken over by Him in the past. I have taken shelter of this āśrama of Vāmana out of devotion for Him.

Now Viśvāmitra concludes the original discussion.

Instead of staying at Rudra’s āśrama that is nearby, why does he reside here? That is answered in the second half of the verse. Viśvāmitra does not misconceive any deity other than Lord Viṣṇu to be the Supreme Being. Out of devotion for Lord Viṣṇu and simply because this is the place of Lord Vāmana, he has taken shelter of it.