One verse

Srimad Bhagavatam 1.4.20

1.4.20

ऋग्यजु:सामाथर्वाख्या वेदाश्चत्वार उद्‍धृता: । इतिहासपुराणं च पञ्चमो वेद उच्यते ॥ २० ॥

rg-yajuh-samatharvakhya vedas catvara uddhrtah itihasa-puranam ca pancamo veda ucyate

rg-yajuh-sama-atharva-akhyah
the names of the four Vedas
vedah
the Vedas
catvarah
four
uddhrtah
made into separate parts
itihasa
historical records (Mahabharata)
puranam ca
and the Puranas
pancamah
the fifth
vedah
the original source of knowledge
ucyate
is said to be.

The four divisions of the original sources of knowledge (the Vedas) were made separately. But the historical facts and authentic stories mentioned in the Puranas are called the fifth Veda.