Lord Caitanya advises that one receive transcendental knowledge from anyone - whether a brahmana or a sudra, a householder or a sannyasi - provided that person is factually conversant with the science of Krsna
SB Canto 3
Vidura said: O Uddhava, because the servants of Viṣṇu, the Lord, wander in the interest of serving others, it is quite fit that you kindly describe the self-knowledge with which you have been enlightened by the Lord Himself.
The servants of the Lord are actually the servants of society. They have no interest in human society other than to enlighten it in transcendental knowledge; they are interested in imparting knowledge of the relationship of the living being with the Supreme Lord, the activities in that transcendental relationship, and the ultimate goal of human life. That is the real knowledge which can help society achieve the real aim of human welfare. Knowledge in the matter of the bodily necessities of eating, sleeping, mating and fearing, transformed into various branches of advancement of knowledge, is all temporary. A living being is not the material body but an eternal part and parcel of the Supreme Being, and thus revival of his self-knowledge is essential. Without this knowledge, the human life is baffled. The servants of the Lord, Viṣṇu, are entrusted with this responsible work, and so they wander over the earth and to all other planets in the universe. Thus the knowledge which was received by Uddhava directly from the Lord deserves to be distributed in human society, especially to persons like Vidura, who are highly advanced in the devotional service of the Lord.
Real transcendental knowledge descends in the disciplic succession from the Lord to Uddhava, from Uddhava to Vidura and so on. Such supreme transcendental knowledge is not possible to achieve by the process of imperfect speculation as performed by the so-called learned mundane wranglers. Vidura was anxious to know from Uddhava that confidential knowledge known as paramāṁ sthitim, in which the Lord is known by His transcendental pastimes. Although Vidura was older than Uddhava, he was anxious to become a servant of Uddhava in the transcendental relationship. This formula of transcendental disciplic succession is taught by Lord Caitanya also. Lord Caitanya advises that one receive transcendental knowledge from anyone—whether a brāhmaṇa or a śūdra, a householder or a sannyāsī—provided that person is factually conversant with the science of Kṛṣṇa. A person who knows the science of Kṛṣṇa is factually a bona fide spiritual master.