Vedavyasasmriti 7

7

śūdro varṇaścaturyo'pi varṇatvāddharmmamarhati .
vedamantrasvadhāsvāhāvaṣaṭ‌kārādibhirvinā .. 1.6 ..

Even the fourth class, the śūdra, is entitled to dharma because he is a class, / without Vedic mantras, the svadhā, the svāhā, the vaṣaṭ exclamation, and the like. // 1.6