It has said that there are only four castes and there is no fifth. The son by the Shudra wife shall take the tenth part of his father's wealth.
स्मृताश्च वर्णाश्चत्वारः पञ्चमो नाधिगम्यते। हरेच्च दशमं भागं शूद्रापुत्रः पितुर्धनात्॥