Apastambadharmasutra 2.6.13

Sons begotten by a man who approaches in the proper season a woman of equal caste, who has not belonged to another man, and who has been married legally, have a right to (follow) the occupations (of their castes),

And to (inherit the) estate,

If they do not sin against either (of their parents).

If a man approaches a woman who had been married before, or was not legally married to him, or, belongs to a different caste, they both commit a sin.

Through their (sin) their son also becomes sinful.

A Brâhmana (says), 'The son belongs to the begetter.'

Now they quote also (the following Gâthâ from the Veda): '(Having considered myself) formerly a father, I shall not now allow (any longer) my wives (to be approached by other men), since they have declared that a son belongs to the begetter in the world of Yama. The giver of the seed carries off the son after death in Yama's world; therefore they guard their wives, fearing the seed of strangers. Carefully watch over (the procreation of) your children, lest stranger seed be sown on your soil. In the next world the son belongs to the begetter, an (imprudent) husband makes the (begetting of) children vain (for himself).'

Transgression of the law and violence are found amongst the ancient (sages).

They committed no sin on account of the greatness of their lustre.

A man of later times who seeing their (deeds) follows them, falls.

The gift (or acceptance of a child) and the right to sell (or buy) a child are not recognised.

It is declared in the Veda that at the time of marriage a gift, for (the fulfilment of) his wishes, should be made (by the bridegroom) to the father of the bride, in order to fulfil the law. 'Therefore he should give a hundred (cows) besides a chariot; that (gift) he should make bootless (by returning it to the giver).' In reference to those (marriage-rites), the word 'sale' (which occurs in some Smritis is only used as) a metaphorical expression; for the union (of the husband and wife) is effected through the law.