One verse

Srimad Bhagavatam 7.15.63

7.15.63

कार्यकारणवस्त्वैक्यदर्शनं पटतन्तुवत् । अवस्तुत्वाद्विकल्पस्य भावाद्वैतं तदुच्यते ॥ ६३ ॥

karya-karana-vastv-aikya- darsanam pata-tantuvat avastutvad vikalpasya bhavadvaitam tad ucyate

karya
the result or effect
karana
the cause
vastu
substance
aikya
oneness
darsanam
observation
pata
the cloth
tantu
the thread
vat
like
avastutvat
because of being ultimately unreality
vikalpasya
of differentiation
bhava-advaitam
the conception of oneness
tat ucyate
that is called.

When one understands that result and cause are one and that duality is ultimately unreal, like the idea that the threads of a cloth are different from the cloth itself, one reaches the conception of oneness called bhavadvaita.