Chandogya Upanishad 8.5.3

8.5.3

atha yad anāśakāyanam ity ācakṣate brahmacaryam eva tat \
eṣa hy ātmā na naśyati yaṃ brahmacaryeṇānuvindate \
atha yad araṇyāyanam ity ācakṣate brahmacaryam eva tat \
tat araś ca ha vai ṇyaś cārṇavau brahmaloke tṛtīyasyām ito divi \
tad airaṃmadīyaṃ saraḥ \
tad aśvatthaḥ somasavanaḥ \
tad aparājitā pūr brahmaṇaḥ prabhuvimitaṃ hiraṇmayam \\805.3\

3. Now, what people call ‘a course of fasting’ (_an-āśakāyana_ ) is really the chaste life of a student of sacred knowledge, for the Soul (Ātman) which one finds through the chaste life of a student of sacred knowledge perishes not (_na naśyati_).

Now, what people call ‘betaking oneself to hermit life in the forest’ (_araṇyāyana_) is really the chaste life of a student of sacred knowledge. Verily, the two seas in the Brahma-world, in the third heaven from here, are _Ara_ and _Ṇya_. There is the lake Airammadīya (‘Affording Refreshment and Ecstasy’);

there, the fig-tree Somasavana (‘the Soma-yielding’); there, Brahma’s citadel, Aparājitā (‘the Unconquered’), the golden hall of the Lord (_prabhu_).