Vedavyasasmriti 6

6

brāhmaṇakṣatriyaviśastrayo varṇāḥ dvijātayaḥ .
śrutismṛtipurāṇoktadharmmayogyāstu netare .. 1.5 ..

Brahmins, kṣatriyas, and vaiśyas are the three classes of twice-born; / they are eligible for the dharma taught by śruti, smṛti, and the Purāṇas, but not the others. // 1.5