ŚB 9.2.9

तं शशाप कुलाचार्य: कृतागसमकामत: ।
न क्षत्रबन्धु: शूद्रस्त्वं कर्मणा भवितामुना ॥ ९ ॥
taṁ śaśāpa kulācāryaḥ
kṛtāgasam akāmataḥ
na kṣatra-bandhuḥ śūdras tvaṁ
karmaṇā bhavitāmunā

Synonyms

tamhim (Pṛṣadhra); śaśāpacursed; kula-ācāryaḥthe family priest, Vasiṣṭha; kṛta-āgasambecause of committing the great sin of killing a cow; akāmataḥalthough he did not want to do it; nanot; kṣatra-bandhuḥthe family member of a kṣatriya; śūdraḥ tvamyou have behaved like a śūdra; karmaṇātherefore by your fruitive reaction; bhavitāyou shall become a śūdra; amunābecause of killing the cow.

Translation

Although Pṛṣadhra had committed the sin unknowingly, his family priest, Vasiṣṭha, cursed him, saying, “In your next life you shall not be able to become a kṣatriya. Instead, you shall take birth as a śūdra because of killing the cow.”

Purport

It appears that Vasiṣṭha was not free from tamo-guṇa, the mode of ignorance. As the family priest or spiritual master of Pṛṣadhra, Vasiṣṭha should have taken Pṛṣadhra’s offense very lightly, but instead Vasiṣṭha cursed him to become a śūdra. It is the duty of a family priest not to curse a disciple but to give him relief through the performance of some sort of atonement. Vasiṣṭha, however, did just the opposite. Therefore Śrīla Viśvanātha Cakravartī Ṭhākura says that he was durmati; in other words, his intelligence was not very good.