Mbh 13.47.2a

"'Bhishma said, "The Brahmana, the Kshatriya, and the Vaisya are regarded as the three regenerate orders. To wed in these three orders has been ordained to be the duty of the Brahmana, O Yudhishthira. Through erroneous judgment or cupidity or lust, O scorcher of foes, a Brahmana takes a Sudra wife. Such a wife, however, he is not competent to take according to the scriptures. A Brahmana, by taking a Sudra woman to his bed, attains to a low end in the next world. He should, having done such an act, undergo expiation according to the rites laid down in the scriptures. That expiation must be twice heavier or severer if in consequence of such an act, O Yudhishthira, the Brahmana gets offspring. I shall now tell thee, O Bharata, how the (paternal) wealth is to be distributed (among the children of the different spouses.) The son born of the Brahmana wife shall, in the first place, appropriate from his father's wealth a bull of good marks, and the best car or vehicle. What remains of the Brahmana's property, O Yudhishthira, after this should be divided into ten equal portions. The son by the Brahmana wife shall take four of such portions of the paternal wealth. The son that is born of the Kshatriya wife is, without doubt, possessed of the status of a Brahmana. In consequence, however, of the distinction attaching to his mother, he shall take three of the ten shares into which the property has been divided. The son that has been born of the wife belonging to the third order, viz., the woman of the Vaisya caste, by the Brahmana sire, shall take, O Yudhishthira, two of the three remaining shares of the father's property. It has been said that the son that has been begotten by the Brahmana sire upon the Sudra wife should not take any portion of the father's wealth, for he is not to be considered an heir. A little, however, of the paternal wealth should be given to the son of the Sudra wife, hence the one remaining share should be given to him out of compassion.