The following is one of the most quoted verses by Srila Prabhupada, from the Srimad Bhagavatam, and it is also one of the longest purports as well. Very important verse!
śrī-prahrādaḥ uvāca—Prahlāda Mahārāja said; śravaṇam—hearing; kīrtanam—chanting; viṣṇoḥ—of LordViṣṇu (not anyone else); smaraṇam—remembering; pāda-sevanam—serving the feet; arcanam—offering worship (with ṣoḍaśopacāra, the sixteen kinds of paraphernalia); vandanaṁ—offering prayers; dāsyam—becoming the servant; sakhyam—becoming the best friend; ātma-nivedanam—surrendering everything, whatever one has; iti—thus; puṁsā arpitā—offered by the devotee; viṣṇau—unto Lord Viṣṇu (not to anyone else); bhaktiḥ—devotional service; cet—if; nava-lakṣaṇā—possessing nine different processes; kriyeta—one should perform; bhagavati—unto the Supreme Personality of Godhead; addhā—directly or completely; tat—that; manye—I consider; adhītam—learning; uttamam—topmost.
Prahlāda Mahārāja said: Hearing and chanting about the transcendental holy name, form, qualities, paraphernalia and pastimes of Lord Viṣṇu, remembering them, serving the lotus feet of the Lord, offering the Lord respectful worship with sixteen types of paraphernalia, offering prayers to the Lord, becoming His servant, considering the Lord one’s best friend, and surrendering everything unto Him (in other words, serving Him with the body, mind and words)—these nine processes are accepted as pure devotional service. One who has dedicated his life to the service of Kṛṣṇa through these nine methods should be understood to be the most learned person, for he has acquired complete knowledge.
When Prahlāda Mahārāja was asked by his father to say something from whatever he had learned, he considered that what he had learned from his spiritual master was the best of all teachings…(from purport)
As spirit souls we are part and parcel of the Supreme Spirit, but due to our desire to enjoy this material world, we have been put into material nature. Yet in whatever species of life we may be, Kṛṣṇa is the Father. Thus Bhagavad-gītā is not meant for any particular party or nation but for everyone all over the world… In this way people may realize their true spiritual nature and their relationship to the supreme spiritual whole.
“And when you have thus learned the truth, you will know that all living beings are but parts of Me—and that they are in Me, and are Mine. Even if you are considered to be the most sinful of all sinners, when you are situated in the boat of transcendental knowledge, you will be able to cross over the ocean of miseries. As a blazing fire burns firewood to ashes, O Arjuna, so does the fire of knowledge burn to ashes all the reactions to material activities.” (Bg. 4.35–37)
Raja-vidya: The King of Knowledge
By His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
Chapter 7
Knowledge as Faith in Guru and surrender to Kṛṣṇa
In the Fourth Chapter of Bhagavad-gītā Śrī Kṛṣṇa concludes that of all sacrifices, the best is the acquisition of knowledge.
“O chastiser of the enemy, the sacrifice of knowledge is greater than the sacrifice of material possessions. O son of Pṛthā, after all, the sacrifice of work culminates in transcendental knowledge.” (Bg. 4.33)
Knowledge is the best sacrifice because this conditional life is due to ignorance. The purpose of sacrifice, penance, yoga and philosophical discussion is to acquire knowledge. There are three stages of transcendental knowledge by which one realizes the impersonal aspect of God (Brahman realization), the localized aspect of God within the heart and within every atom (Paramātmā or Supersoul realization) and the realization of the Supreme Personality of Godhead (Bhagavān realization). But the very first step in acquiring knowledge is coming to understand that “I am not this body. I am spirit soul, and my aim of life is to get out of this material entanglement.” The point is that whatever sacrifice we make is intended to enable us to come to the point of real knowledge. The highest perfection of knowledge is given in Bhagavad-gītā as surrender to Kṛṣṇa (bahūnāṁ janmanām ante jñānavān māṁ prapadyate) (Bg. 7.19). The jñānavān, not the fool, surrenders unto Kṛṣṇa, and that is the highest stage of knowledge. Similarly, at the end of Bhagavad-gītā Śrī Kṛṣṇa advises Arjuna:
In the Bhagavad-gītā also the Lord says: “Give up all your occupations and just become surrendered unto Me. I give you assurance that I shall give you protection from all sinful reactions.” One may think that because he is surrendering unto the Supreme Personality of Godhead, he will not be able to perform all of his other obligations. But the Lord says repeatedly, “Don’t hesitate. Don’t consider that because you are giving up all other engagements there will be some flaw in your life. Don’t think like that. I will give you all protection.” That is the assurance of Lord Kṛṣṇa in the Bhagavad-gītā.
The Nectar of Devotion – 1970 Edition
By His Divine Grace A.C. Bhaktivedanta Swami Prabhupada
Chapter 5
Purity of Devotional Service
All of the previous instructions imparted by Śrīla Rūpa Gosvāmī in his broad statements can be summarized thus: as long as one is materially inclined or desirous of merging into the spiritual effulgence, one cannot enter into the realm of pure devotional service. Next, Rūpa Gosvāmī states that devotional service is transcendental to all material considerations and that it is not limited to any particular country, class, society or circumstance. As stated in Śrīmad-Bhāgavatam, devotional service is transcendental and has no cause. Devotional service is executed without any hope for gain, and it cannot be checked by any material circumstances. It is open for all, without any distinction, and it is the constitutional occupation of the living entities.
The Hare Krishna Movement 