Bhagavad Gita 1.42

Promiscuity ruins both the family and those who defile it; while the souls of our ancestors droop, due to the lack of funeral cakes and ablutions.

सङ्करो नरकायैव कुलघ्नानां कुलस्य च।
पतन्ति पितरो ह्येषां लुप्तपिण्डोदकक्रियाः॥

saṅkaro narakāyaiva kulaghnānāṃ kulasya ca|
patanti pitaro hyeṣāṃ luptapiṇḍodakakriyāḥ||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).