Bhagavad Gita 1.40
The destruction of our kindred means the destruction of the traditions of our ancient lineage, and when these are lost, irreligion will overrun our homes.
कुलक्षये प्रणश्यन्ति कुलधर्माः सनातनाः।
धर्मे नष्टे कुलं कृत्स्नमधर्मोऽभिभवत्युत॥kulakṣaye praṇaśyanti kuladharmāḥ sanātanāḥ|
dharme naṣṭe kulaṃ kṛtsnamadharmo'bhibhavatyuta||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).