vikṛtiṃ naiva gacchanti

vikṛtiṃ naiva gacchanti saṅgadoṣeṇa sādhavaḥ |

āveṣṭitaṃ mahāsarpaiścandanaṃ na viṣāyate ||

Bad company does not induce changes (bad habits) in a good person, just like (poisonous) snakes on sandal trees does not cause that tree to become poisonous.