Discourse on Bhagavad Gītā 8.19-20.
bhūta-grāmaḥ sa evāyaṁ
bhūtvā bhūtvā pralīyate
rātry-āgame ’vaśaḥ pārtha
prabhavaty ahar-āgame
“Again and again, when Brahmā’s day arrives, all living entities come into being, and with the arrival of Brahmā’s night they are helplessly annihilated.”
paras tasmāt tu bhāvo ’nyo
’vyakto ’vyaktāt sanātanaḥ
yaḥ sa sarveṣu bhūteṣu
naśyatsu na vinaśyati
“Yet there is another unmanifest nature, which is eternal and is transcendental to this manifested and unmanifested matter. It is supreme and is never annihilated. When all in this world is annihilated, that part remains as it is.”