As servants of the Supreme Lord, all living entities are one, but a Vaiṣṇava, because of his natural humility,addresses every other living entity as prabhu. A Vaiṣṇava sees other servants to be so advanced that he has much to learn from them. Thus he accepts all other devotees of the Lord as prabhus, masters. Although everyone is a servant of the Lord, one Vaiṣṇava servant, because of humility, sees another servant as his master. Understanding of the master begins from understanding of the spiritual master.
(Srimad Bhagavatam----7:5:11----purport).

When Pṛthu Mahārāja became spiritually powerful by the enhancement of his spiritual knowledge (jñāna) and renunciation of material desires, he became a prabhu, or master of his senses (sometimes called gosvāmī or svāmī). This means that he was no longer controlled by the influence of material energy. When one is strong enough to give up the influence of material energy, he iscalled prabhu. In this verse the word svarūpa-sthaḥ is also very significant. The real identity of the individual soul lies in understanding or attaining the knowledge that he is eternally a servant of Kṛṣṇa. This understanding is called svarūpopalabdhi. By culturing devotional service, the devotee gradually comes to understand his actual relationship with the Supreme Personality of Godhead. This understanding of one's pure spiritual position is called svarūpopalabdhi, and when one attains that stage he can understand how he is related with the Supreme Personality of Godhead as a servant or friend or as a parent or conjugal lover. This stage of understanding is called svarūpa-sthaḥ. Pṛthu Mahārāja realized this svarūpa completely, and it will be clear in the later verses that he personally left this world, or this body, by riding on a chariot sent from Vaikuṇṭha. In this verse the word prabhu is also significant. As stated before, when one is completely self-realized and acts according to that position, he can be called prabhu. The spiritual master is addressed as "Prabhupāda" because he is a completely self-realized soul. The word pāda means "position," and Prabhupāda indicates that he is given the position of prabhu, or the Supreme Personality of Godhead, for he acts on behalf of the Supreme Personality of Godhead. Unless one is a prabhu, or controller of the senses, he cannot act as spiritual master, who is authorized by the supreme prabhu, or Lord Kṛṣṇa.
(Srimad Bhagavatam----4:23:18----purport).

A fraction of a particular thing is called a part, and that from which the fraction is distinguished is called the whole. Therefore the fraction, or part, is included within the whole. The Lord is the whole, and the devotee is the part or fractional part. That is the relationship between the Lord and the devotee. There are also gradations of devotees, who are calculated as greater or lesser. When a devotee is great he is called prabhu, and when he is lesser he is called bhakta, or a devotee. The supreme whole is Kṛṣṇa, and Baladeva and all Viṣṇu incarnations are His fractions. Lord Kṛṣṇa is therefore conscious of His superior position, and all Viṣṇu incarnations are conscious of Their positions as devotees.
(Sri Caitanya Caritamrta----1:6:99----purport).

Śrī Caitanya Mahāprabhu, Advaita Prabhu and Nityānanda Prabhu all belong to the viṣṇu-tattva category. Because Lord Caitanya is an ocean of mercy, He is addressed as mahāprabhu, whereas Nityānanda and Advaita, being two great personalities who assist Lord Caitanya, are addressed as prabhu. Thus there are two prabhus and one mahāprabhu. Gadādhara Gosvāmī is a representative of a perfect brāhmaṇa spiritual master. Śrīvāsa Ṭhākura represents a perfect brāhmaṇa devotee. These five are known as the Pañca-tattva.
(Sri Caitanya Caritamrta----1:17:301----purport).

In this verse the word prabhupāda, referring to Śrī Caitanya Mahāprabhu, is significant. Regarding this, Śrīla Bhaktisiddhānta Sarasvatī Gosvāmī Prabhupāda comments, “Śrī Caitanya Mahāprabhu is the Supreme Personality of Godhead Himself, Śrī Kṛṣṇa, and all His servants address Him as Prabhupāda. This means that there are many prabhus taking shelter under His lotus feet.” The pure Vaiṣṇava is addressed as prabhu, and this address is an etiquette observed between Vaiṣṇavas. When many prabhus remain under the shelter of the lotus feet of another prabhu, the address Prabhupāda is given. Śrī Nityānanda Prabhu and Śrī Advaita Prabhu are also addressed as Prabhupāda. Śrī Caitanya Mahāprabhu, Śrī Advaita Prabhu and Śrī Nityānanda Prabhu are all viṣṇu-tattva, the Supreme Personality of Godhead, Lord Viṣṇu. Therefore all living entities are under Their lotus feet. Lord Viṣṇu is the eternal Lord of everyone, and the representative of Lord Viṣṇu is the Lord’s confidential servant. Such a person acts as the spiritual master for neophyte Vaiṣṇavas; therefore the spiritual master is as respectable as Śrī Kṛṣṇa Caitanya or Lord Viṣṇu Himself. For this reason the spiritual master is addressed as Oṁ Viṣṇupāda or Prabhupāda. The ācārya, the spiritual master, is generally respected by others as Śrīpāda, and the initiated Vaiṣṇavas are addressed as Prabhu. Prabhu, Prabhupāda and Viṣṇupāda are described in revealed scriptures like Śrīmad-Bhāgavatam, Caitanya-caritāmṛta and Caitanya-bhāgavata. In this regard, these scriptures present evidence accepted by unalloyed devotees.
(Sri Caitanya Caritamrta----2:10:23----purport).

Seeing the sublime character of the prostitute, everyone was astonished. Everyone glorified the influence of Haridāsa Ṭhākura and offered him obeisances. It is said, phalena paricīyate: one is recognized by the result of his actions. In Vaiṣṇava society there are many types of Vaiṣṇavas. Some of them are called gosvāmīs, some are called svāmīs, some are prabhus, and some are prabhupāda. One is not recognized, however, simply by such a name. A spiritual master is recognized as an actual guru when it is seen that he has changed the character of his disciples. Haridāsa Ṭhākura actually changed the character of the professional prostitute. People greatly appreciated this, and therefore they all offered obeisances to Haridāsa Ṭhākura and glorified him.
(Sri Caitanya Caritamrta----3:3:143---translation and purport).

One has to become purified by freeing himself from all designations. This is the first step. We are now under different designations. Every one of us is thinking that "I am this body, and because I am this body and this body is produced under certain condition, in a certain family, by certain father and mother, in a certain society, certain country, certain land, therefore I have got, you have got so many designations." But we have to become first of all free from the designations. That is the first qualification for understanding the science of God. We have to become free from all designations. And how one can become free? This is Kṛṣṇa consciousness. I am neither Indian, I am neither American, I am neither white, I am neither black, I am neither Christian, I am neither Hindu, Muhammadan. Caitanya Mahāprabhu described Himself like that. He said, "I am not a brāhmaṇa, I am not a kṣatriya, I am not a vaiśya, I am not a śūdra, I am not a brahmacārī, I am not a householder, I am not a vānaprastha, or I am not a renounced order sannyāsī." Then what You are? Caitanya Mahāprabhu said, gopī-bhartuḥ pada-kamalayor dāsa-dāsānudāsaḥ [Cc. Madhya 13.80]. "I am the servant of the servant of the servant of the servant of Kṛṣṇa." This should be my real identification. This is very good identification. In Kṛṣṇa consciousness we address our contemporaries as "prabhu." Prabhu means master. And the real idea is that "You are my master, I am your servant." Just the opposite number. Here, in the material world, everyone wants to place himself as the master. "I am your master, you are my servant." That is the mentality of material existence. And the spiritual existence means "I am the servant, you are the master." Just see. Just the opposite number.
(Lecture on Bhagavad-Gita---4:9).

So showing respect to the constable in the street means showing respect to the government, not to that particular person. So these things are there in the Vedic literatures. But if you want some favors from the police officer, then you are also entangled, and that police officer is also entangled. You have to go by the rules. But one who is directly in touch of the Supreme Lord, they do not require to worship any other... Because actually... Suppose a man is personally in contact with your President Johnson. That does not mean he'll disobey the constable. No. Naturally he will obey, although he's direct contact. Similarly, those who are in direct contact with the Supreme Personality of Godhead, they have no disregard for these demigods, but they know the ultimate supreme power is the Supreme Personality of Godhead. They have got that knowledge. So their surrender is there in the Supreme Lord, not here. But they are not going to show any disrespect. A real devotee, he does not show any disrespect even to the ant, and what to speak of the demigods, because he is in knowledge that "Every living entity is part and parcel of the Supreme Lord. They're playing different parts only. So in relationship with the Supreme Lord they're all my respectables." Therefore a devotee is taught to address all his contemporaries as "Prabhu, my dear sir, my dear lord." That is the position of Kṛṣṇa consciousness. They are not heartless. They are very submissive.
(Lecture on Bhagavad-Gita---7:18).

We are teaching our disciples to address amongst themselves "prabhu." This is not new thing. This is very old. Now Nārada is addressing Vyāsadeva, "prabhu," his disciple. His disciple, he's addressing prabhu. So we should give respect. Just like we address, "Kīrtanānanda Mahārāja." Although he's my disciple, but the respect should be given. Here, see, Nārada is addressing Vyāsadeva: "Prabhu." "My dear prabhu, still you are lamenting. You have done so nice, wonderful things and you are learned, you have asked about the transcendental subject matter, you have compiled so many nice books. Why? Why you are?" This question must be there just to apprehend that "What is the reason?" So this is the question and answer of Vyāsadeva. It is very interesting. You have got already your book, Śrīmad-Bhāgavatam, Fifth Chapter, First Canto. They are very interesting. So we shall discuss.
(Lecture on Srimad Bhagavatam---1:5:1-4).

So apy adya nas tvaṁ sva-kṛtehita prabho. Now Kṛṣṇa is addressed as prabhu. Although Kṛṣṇa has come to Kuntīdevī to take the dust of his feet, of her feet—she's superior aunt—but Kuntīdevī is addressing Him the prabhu, the Lord. Kuntīdevī is not addressing Him... She's asking her beloved nephew... But He, she knows that "Kṛṣṇa, although playing the part of my nephew, my brother's son, still He's Prabhu, He's the supreme master." Therefore she's addressing Him, "Prabhu." Jihāsasi. Jihāsasi means, "Are You actually leaving us?" Jihāsasi svit suhṛdaḥ. Suhṛdaḥ means those who are well-wishers. Anujīvinaḥ. Anujīvinaḥ means, "They are living under Your mercy only. Our life is always under Your mercy."
(Lecture on Srimad Bhagavatam---1:8:37).

Those who are learned devotees, advanced devotees, they also accept this that spiritual master should be treated as good as Hari, the Supreme Person. Why? Now...
But the spiritual master does not think of himself as Hari. Although he's offered the respect of Hari, he thinks himself as humble servant of Hari and all others. A spiritual master takes his devo..., disciples as his spiritual master. That is the position. He thinks that "Kṛṣṇa has sent me so many spiritual masters." He does not think himself as spiritual master. He thinks himself their servant. Because they have to be trained. Kṛṣṇa has appointed him to train them. Therefore he thinks himself as servant of the disciples. This is the position. So when one is advanced, he can see the importance of devotees.
Advanced devotee never disobey or disrespect another devotee. Disrespect to another devotee is a great offense. Vaiṣṇava aparādha. Vaiṣṇava aparādha is very serious offense. Thereforewe teach to address amongst the devotees, "Prabhu", "Prabhu", "Such and such Prabhu." This should not be simply spoken by the lips. It should be realized. Everyone should think other devotee as his prabhu, master. Not he should try to become master.
(Lecture on Nectar of Devotion).

If one fights like cats and dogs, he becomes cats and dogs. Nature's law is very strict. Therefore we should be very careful not to become like cats and dogs but to become very humble—humbler than the grass and tolerant than the tree. Amāninā. Everyone wants that "I am very honorable man, prestigious man. And you should respect me." That is our material disease. "I do not want to respect you, but you should offer me respect." This is the position. Therefore our system is to call another Vaiṣṇava as prabhu. "Sir, you are prabhu, you are master." But we call prabhu, but I think, "No, you are not prabhu; I am prabhu. You are servant." This cheating process will not help us. Actually, we should believe that he is prabhu. "He is servant of Kṛṣṇa; therefore he is my prabhu." This is Vaiṣṇava mentality. Gopī-bhartur pada-kamalayor dāsa-dāsa-dāsa-dāsānudāsa. One who wants to become servant of the servant of the servant of the servant, he is actually prabhu [Cc. Madhya 13.80]. If falsely one thinks that "I am prabhu," then his life is spoiled. So this word we use amongst ourself, prabhu, means that "I am your servant, you are my master." But that should be practically exhibited. That is called tapasya, to learn all these things.
(Lecture on Srimad Bhagavatam---5:5:1).