Sometimes people do not accept the Purāṇas as Vedic. No. Here it is said by Rūpa Gosvāmī, śruti-smṛti-purāṇādi (Brs. 1.2.101). They are all Vedas. Purāṇa means supplementary. Just like the Vedic knowledge is described in the Mahābhārata. It is in the form of history. But actually the Vedic knowledge is there. That is also stated in the Śrīmad-Bhāgavatam, strī-śūdra-dvija-bandhūnāṁ trayī na śruti-gocaraḥ (SB 1.4.25). Strī, woman, śūdra, and dvija-bandhu... Dvija-bandhu means a person who is born in brāhmaṇa family but he is not advanced in spiritual knowledge. He is called dvija-bandhu. He is not called a brāhmaṇa. Strī, śūdra. And they are classified along with strī and śūdra. Strī-śūdra-dvija-bandhūnāṁ trayī na śruti-gocaraḥ. For these persons it is very difficult to understand the Vedic injunctions. Therefore the Vedic injunctions are sometimes made into historical stories. The stories, they are not fiction; they are fact. But some of the... Just like the Battle of Kurukṣetra between the Pāṇḍavas and the Kauravas, this is a fact. But the incidences are so nice that you can derive Vedic knowledge from them. And Bhagavad-gītā is within Mahābhārata.
So this is a fact, that veda-praṇihito dharmaḥ. Dharma... It is to be settled up that dharma means the injunction of the Supreme Nārāyaṇa. And adharma means that you manufacture something out of your own fertile brain. That is adharma. And dharma means the injunction. Dharmāṁ (tu) sākṣād bhagavat-praṇītam: (SB 6.3.19) "Dharma means what is spoke by the Supreme Personality of Godhead, that is dharma." Therefore we take it for acceptance that Kṛṣṇa says... That is actually the fact. Mām ekaṁ śaraṇaṁ vraja. To surrender unto Kṛṣṇa, that is dharma. Sarva-dharmān parityajya (BG 18.66).