Vaishnava Samhita. Raskhan Charitam. Vol III Book VII Chp 13 Shlokas 9 - 10

दुराचारेण सम्युक्तान् कृष्णकीर्तनतत्परान् |

आश्लिष्य प्रणमेद्भक्तश्चण्डालानपि पामरान् ||

वर्णाश्रमकुलाचारो विहितो ह्मात्मशुद्धये |

कुर्वन्ति डाम्भिका मर्त्याः परस्परविदूषकाः ||

A bhakta should embrace them and bow to those chandalas who do Krishna kirtan, though being ignorant and bad-conducted. Restrictions were attached with caste system and lineage only to ensure purity of hearts. But they are observed by the pedagogues only to despise one another.