One verse

Srimad Bhagavatam 10.47.32

10.47.32

येनेन्द्रियार्थान् ध्यायेत मृषा स्वप्नवदुत्थित: । तन्निरुन्ध्यादिन्द्रियाणि विनिद्र: प्रत्यपद्यत ॥ ३२ ॥

yenendriyārthān dhyāyeta mṛṣā svapna-vad utthitaḥ tan nirundhyād indriyāṇi vinidraḥ pratyapadyata

yena
by which (mind)
indriya
of the senses
arthān
upon the objects
dhyāyeta
one meditates
mṛṣā
false
svapna-vat
like a dream
utthitaḥ
arisen from sleep
tat
that (mind)
nirundhyāt
one should bring under control
indriyāṇi
the senses
vinidraḥ
not sleeping (alert)
pratyapadyata
they obtain

As a person just arisen from sleep may continue to meditate on a dream even though it is illusory, so by the agency of the mind one meditates on the sense objects, which the senses can then obtain. Therefore one should become fully alert and bring the mind under control.