CC Madhya 10.136

eta śuni’ sārvabhauma prabhure puchila
purī-gosāñi śūdra-sevaka kāṅhe ta’ rākhila
Word for word: 
eta śuni’ — hearing this; sārvabhauma — Sārvabhauma Bhaṭṭācārya; prabhure — unto the Lord; puchila — inquired; purī-gosāñi — Īśvara Purī; śūdra-sevaka — a servant who is a śūdra; kāṅhe ta’ — why; rākhila — kept.
Translation: 
After hearing this, Sārvabhauma Bhaṭṭācārya asked Śrī Caitanya Mahāprabhu, “Why did Īśvara Purī keep a servant who comes from a śūdra family?”
Purport: 

Both Kāśīśvara and Govinda were personal servants of Īśvara Purī. After Īśvara Purī’s demise, Kāśīśvara went to visit all the holy places of India. Following the orders of his spiritual master, Govinda immediately went to Śrī Caitanya Mahāprabhu for shelter. Govinda came from a śūdra family, but because he was initiated by Īśvara Purī, he was certainly a brāhmaṇa. Sārvabhauma Bhaṭṭācārya here asked Śrī Caitanya Mahāprabhu why Īśvara Purī accepted a disciple from a śūdra family. According to the smṛti-śāstra, which gives directions for the management of the varṇāśrama institution, a brāhmaṇa cannot accept a disciple from the lower castes. In other words, a kṣatriya, vaiśya or śūdra cannot be accepted as a servant. If a spiritual master accepts such a person, he is contaminated. Sārvabhauma Bhaṭṭācārya therefore asked why Īśvara Purī accepted a servant or disciple born of a śūdra family.

In answer to this question, Śrī Caitanya Mahāprabhu replied that His spiritual master, Īśvara Purī, was so empowered that he was as good as the Supreme Personality of Godhead. As such, Īśvara Purī was the spiritual master of the whole world. He was not a servant of any mundane rule or regulation. An empowered spiritual master like Īśvara Purī can bestow his mercy upon anyone, irrespective of caste or creed. The conclusion is that an empowered spiritual master is authorized by Kṛṣṇa and his own guru and should therefore be considered as good as the Supreme Personality of Godhead Himself. That is the verdict of Viśvanātha Cakravartī: sākṣād-dharitvena. An authorized spiritual master is as good as Hari, the Supreme Personality of Godhead. As Hari is free to act as He likes, the empowered spiritual master is also free. As Hari is not subject to mundane rules and regulations, the spiritual master empowered by Him is also not subject. According to the Caitanya-caritāmṛta (Antya-līlā 7.11), kṛṣṇa-śakti vinā nahe tāra pravartana. An authorized spiritual master empowered by Kṛṣṇa can spread the glories of the holy name of the Lord, for he has power of attorney from the Supreme Personality of Godhead. In the mundane world, anyone possessing his master’s power of attorney can act on behalf of his master. Similarly, a spiritual master empowered by Kṛṣṇa through his own bona fide spiritual master should be considered as good as the Supreme Personality of Godhead Himself. That is the meaning of sākṣād-dharitvena. Śrī Caitanya Mahāprabhu therefore describes the activities of the Supreme Personality of Godhead and the bona fide spiritual master as follows.