sa evāyaḿ mayā te ‘dya
yogaḥ proktaḥ purātanaḥ
bhakto ‘si me sakhā ceti
rahasyaḿ hy etad uttamam

Translation of Bhagavad Gita 4.3

That very ancient science of the relationship with the Supreme is today told by Me to you because you are My devotee as well as My friend and can therefore understand the transcendental mystery of this science.

Commentary by Sri A.C. Bhaktivedanta Swami Prabhupada of Gaudiya Sampradaya:

There are two classes of men, namely the devotee and the demon. The Lord selected Arjuna as the recipient of this great science owing to his being a devotee of the Lord, but for the demon it is not possible to understand this great mysterious science. There are a number of editions of this great book of knowledge. Some of them have commentaries by the devotees, and some of them have commentaries by the demons. Commentation by the devotees is real, whereas that of the demons is useless. Arjuna accepts Sri Krishna as the Supreme Personality of Godhead, and any commentary on the Gita following in the footsteps of Arjuna is real devotional service to the cause of this great science. The demonic, however, do not accept Lord Krishna as He is. Instead they concoct something about Krishna and mislead general readers from the path of Krishna’s instructions. Here is a warning about such misleading paths. One should try to follow the disciplic succession from Arjuna, and thus be benefitted by this great science of Srimad Bhagavad-gita.

Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

In this verse, the Lord gives the reason for speaking this yoga to Arjuna. You are my devotee (my servant) and my friend. Apart from these two reasons, he gives another reason for speaking to a person favorable to him: it is private or secret.

Commentary by Sri Ramanuja of Sri Sampradaya:

4.3 It is the same ancient, unchanged Yoga which is now taught to you, who out of friendship and overwhelming devotion have resorted to Me whole-heartedly. The meaning is that it has been taught to you fully with all its accessories. Because it is the most mysterious knowledge declared in the Vedanta, it cannot be known or taught by anyone other than Myself. In this connection, in order to know the truth about the Lord’s descent correctly, Arjuna asked:

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

Now Lord Krishna is confirming that the very same eternal yoga or science of the individual consciousness attaining communion with the ultimate consciousness that had become lost and disappeared is being taught again in parampara or disciplic succession to His friend Arjuna because he is His disciple. It was not taught by Lord Krishna to others outside of parampara because it is highly confidential and a supreme secret.

Commentary by Sri Madhvacharya of Brahma Sampradaya:

Hari OM! In this chapter the superiority of the intellect having its power of discrimination, the greatness of the atma or soul possessing its eternal nature, the importance of the performance of karma yoga or prescribed Vedic activities according to position and stage in life and the supremacy of jnana yoga or the cultivation of Vedic wisdom. Whatever Lord Krishna has delineated in the previous three chapters should be understood to be dharma or absolute principles of eternal righteousness. This is what is meant by the word iman which means this and refers to the science of yoga which is the science of the individual consciousness in communion with the Ultimate Consciousness. Lord Krishna wants to impress upon posterity that what He is explaining is not temporary relating to time and circumstances but is nitya tattva or eternal truths and rita or inviolable cosmic laws. They never become outdated nor do they become irrelevant with the passage of time. They are always relevant, constantly renewing themselves, remaining ever fresh as nature is in the universe. Nature as was created in the beginning of time and nature as is present now in the world is not different in their essence although there may be difference in the form; but form is but a manifestation it is not the essence. Because of the atrophy of human receptivity and the excess of human depravity along with a decline in human intellect there comes about obscurity in human perception. Therefore from time to time the ashes that are covering the coals need to be brushed away for the embers which were hidden to glow in their eternal splendour. Sometimes the Supreme Lord Himself in His avatara forms as scripturally authorised incarnations manifests and incarnates to periodically re- establish these eternal principles of creation. At other times great souls from the higher realms with exceptional compassion descend and see a need to reiterate and disseminate these divine principles for all of humanity suffering in the perpetual cycle of birth and death. These great souls never modify the intrinsic meaning of these eternal principles nor do they change the essential characteristics of these eternal principles although they make innovations in their preaching and how they distribute them according to time and circumstance. They have nothing new to instruct nor anything to add they merely come to remove aside the ash that has covered the glowing embers of eternal principles and to prepare conditions so that beguiled humanity may have the greatest opportunity to be receptive to these eternal principles.

Now begins the summation.

Hari Om! The wisdom and performance of eternal spiritual principles as given in the Vedic scripture Pancaratra which Lord Krishna aeons before had instructed in initiation to Brahma, Shiva, Indra and Surya the sun-god is again being explained to the Pandavas as the eternal principles of the Bhagavad-Gita which is the abridged form of the Pancaratra and the essence of all Vedic scriptures. The manner in which the demi-gods, the great sages, the saintly kings and how human beings should achieve Vedic wisdom by performing karma yoga in Satya, Treta, Dwarpa and kali yugas or the four measurements of Vedic duration comprising a period of 1, 360, 000 years. All these things are explained in the Bhagavad-Gita. From Arjuna to Manu, all perform karma yoga and gain Vedic wisdom as prescribed in the Bhagavad- Gita. The Brahma Vaivarta Purana states that there is no Vedic scripture superior to the Bhagavad-Gita. The Pancaratra which is supplementary to the four Vedas should be learned and assimilated in its entirety and the Bhagavad-Gita is its essence. Thus there is nothing that can compare to the illustrious Bhagavad-Gita.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

Lord Krishna now confirms that the same eternal yoga or science of the individual consciousness attaining communion with the ultimate consciousness that was imparted aeons before to Visvavan is being instructed to His friend Arjuna and no one else. Why no one else? Because Arjuna was qualified to receive this yoga, and because he was Lord Krishna’s surrendered disciple. As this yoga is highly confidential it should not be revealed to those who have no faith nor to those who are unqualified.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

4.3 Sah, that; puratanah, ancient; yogah, Yoga; eva, itself; ayam, which is this; proktah, has been taught; te, to you; maya, by Me; adya, today; iti, considering that; asi, you are; me, My; bhaktah, devotee; ca sakha, and friend. Hi, for; etat, this Yoga, i.e. Knowledge; is a uttamam, profound; rahasyam, secret. Lest someone should understand that the Lord has said something contradictory, therefore, in order to prevent that (doubt), as though raising a question,

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

4.1-3 Evam etc. upto uttamam. Eventhough it has come down by regular succession of teacher, it is lost now. By this [statement] the Bhagavat indicates the rarity (or difficulty) and respectability of this knowledge. You are My devotee and friend too : You are a devotee having nothing but Me as your final goal and you are a friend too. This ‘too’ indicates the secondary importance [of the friendship]. Hence, just as in the sentence ‘wander begging food [etc]’, the importance lies in the act of begging food, but unimportance in the act of bringing the cow; in the same way, in the present case it is devotion towards the teacher that is important and not the friendship also. This is the idea intended here.

Sanskrit Shloka Without Transliteration Marks:

sa evayam maya te ‘dya
yogah proktah puratanah
bhakto ‘si me sakha ceti
rahasyam hy etad uttamam

Sanskrit to English Word for Word Meanings:

saḥ — the same; eva — certainly; ayam — this; mayā — by Me; te — unto you; adya — today; yogaḥ — the science of yoga; proktaḥ — spoken; purātanaḥ — very old; bhaktaḥ — devotee; asi — you are; me — My; sakhā — friend; ca — also; iti — therefore; rahasyam — mystery; hi — certainly; etat — this; uttamam — transcendental.