Manava Dharmashastra 3.15

3.15

pūrvasya pratiṣedhasya śeṣoyaṃ nindārthavādaḥ | hīnajātiḥ śūdraiva, tasyā eva prakṛtatvāt, sasantānāni śūdratāmiti. nigamanāt | ta ete dvijātayaḥ mohāddhanalobhājādvivekātkāmanimittatvādva| kulāni śūdratāṃ gamayanti | tasyāṃ jātāḥ putrāḥ śūdrā bhavantyeva tatputrapautrā iti | ata ucyate sasantānānīti | santāno'patyotpattiprabandhaḥ putrapautrādiḥ |
21) ityanena nyāyenāprasiddhasya dṛṣṭāntatāstīti | vidhirapi dṛṣṭāntavacanādeva śakyo'vagantum |

Medhātithi’s commentary (manubhāṣya):
This is a deprecatory exhortation, supplementing the foregoing prohibition.

‘Of the lout caste’—i.e., of the Śūdra caste; the Śūdra girl being the subject of consideration; and further, because the statement ends with the assertion that the families along with offspring are reduced to the position of the Śūdra.

‘The twice-born men, through infatuation’—i.e., on account of folly arising from greed for wealth, or from lust,—‘reduce their families to the position of the Śūdra.’ That is, sons born of that wife become Śūdras, and so also grandsons and great-grandsons descended from them. Hence, it is added—‘along with their offspring’—the term ‘offspring’ standing for the line of descendants, consisting of sons, grandsons, &c.—(15).