Bhagavatapurana 3.9.37

3.9.37

tubhyaṃ mad-vicikitsāyām ātmā me darśito 'bahiḥ /
nālena salile mūlaṃ puṣkarasya vicinvataḥ //

37. When through the stalk thou soughtest to know the lotus root (*i.e.*, the cause) under water, and when a question arose in thy mind as to the existence of the cause (regarding Me), My true nature was revealed to thee in thine own mind (lit. not outside).