One verse

Srimad Bhagavatam 6.1.49

6.1.49

यथाज्ञस्तमसा युक्त उपास्ते व्यक्तमेव हि । न वेद पूर्वमपरं नष्टजन्मस्मृतिस्तथा ॥ ४९ ॥

yathajnas tamasa yukta upaste vyaktam eva hi na veda purvam aparam nasta-janma-smrtis tatha

yatha
just as
ajnah
an ignorant living being
tamasa
in sleep
yuktah
engaged
upaste
acts according to
vyaktam
a body manifested in a dream
eva
certainly
hi
indeed
na veda
does not know
purvam
the past body
aparam
the next body
nasta
lost
janma-smrtih
the remembrance of birth
tatha
similarly.

As a sleeping person acts according to the body manifested in his dreams and accepts it to be himself, so one identifies with his present body, which he acquired because of his past religious or irreligious actions, and is unable to know his past or future lives.