The son begotten by a Brahmana upon a Shudra wife is called Parashva, meaning one bom of a dead body for the Shudra woman's body is as inauspicious as a dead body. He should serve the persons of his (father's) race. Indeed, it is not proper for him to renounce the duty of service that has been laid down for him.
परं शवाद् ब्राह्मणस्यैव पुत्रः शूद्रापुत्रं पारशवं तमाहुः। शुश्रूषकः स्वस्य कुलस्य स स्यात् स्वचारित्रं नित्यमथो न जह्यात्॥