BG 1.42
पतन्ति पितरो ह्येषां लुप्तपिण्डोदकक्रियाः ॥
patanti pitaro hy eṣāṁ lupta-piṇḍodaka-kriyāḥ
Word-for-word meanings
saṅkaraḥ — the intermingling [of social classes]; narakāya — results in hell; eva — only; kula-ghnānām — for the destroyers of the family; ca — and; kulasya — for the family itself; eṣām — their; pitaraḥ — ancestors; patanti — fall down; hi — certainly; lupta — being deprived; kriyāḥ — [of] the ceremonies; piṇḍa — of offering rice; udaka — [and] water.
Translation
The intermingling of social classes results only in hell for the destroyers of the family as well as for the family itself. Their ancestors certainly also glide down, being deprived of the ceremonial offerings of rice and water*.
Notes
* This refers to the ritual of śrāddha and tarpaṇa for the departed ancestors called pitṛs. Such an offering by the descendants sustains the pitṛs in the heavenly abode called pitṛ-loka. In return they bless their descendants. The progeny born from illegitimate intermingling of classes are disqualified to perform the ceremonies of śrāddha and tarpaṇa.