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

Expressions researched:
"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"

SB Canto 1

Purāṇas are called the fifth Veda.

SB 1.4.20, Translation:

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