Revākhaṇḍa ascribed to the Vāyupurāṇa (RKV) 142.54

142.54

vasiṣṭhaṃ ca mahābhāgamityete sapta mānasāḥ /
ityete brāhmaṇāḥ sapta purāṇe niścayaṃ gatāḥ //

and the illustrious Vasiṣṭha—these are the seven mind-born [sons of Brahmā]. / These seven brāhmaṇas are ascertained in the Purāṇa;