Bhagavad Gita 5.18

तद्बुद्धयस्तदात्मानस्तन्निरास्तत्परायणा: |
गच्छन्त्यपुनरावृत्तिं ज्ञाननिर्धूतकल्मषाः

Translation

The truly learned, with the eyes of divine knowledge, see with equal vision a Brahmin, a cow, an elephant, a dog, and a dog-eater.