tvaṁ hi brahma-vidāṁ śreṣṭhaḥ saṁskārān kartum arhasi
tvaṁ hi brahma-vidāṁ śreṣṭhaḥ saṁskārān kartum arhasi |
bālayor anayor nṝṇāṁ janmanā brāhmaṇo guruḥ ||
(Śrīmad Bhāgavatam: 10.8.6)
“[Nanda Mahārāja to Garga Muni:] Since you are the best of knowers of Brahman, you are fit to perform the saṁskāras for these two boys [viz., Kṛṣṇa and Balarāma]. A brāhmaṇa by birth is the guru of human beings.”