Srimad Bhagavad-Gita :
Chapter-9. ( Raja-vidya-raja-guhya-yogam )
Slokam-20. ( Those who study the Vedas and drink the soma juice, seeking the heavenly planets, worship Me indirectly. They take birth on the planet of Indra, where they enjoy godly delights. )
traividya mam somapah putapapah
yajnairishtva svargatim prarthayante
te punyamasadya surendralokam
asnanti divyan divi devabhogan.
traividyah = who practicing Vedic rituals ( karma/activities);
yajnairiah mam ishtva = worshipping Me with yaga-s;
somapah = drinkers of soma-rasam;
putapapah = purified the sins;
svargatim prarthayante = pray for the passage to heaven;
te punyamasadya surendralokam = they the holy indralokam;
asadya divi = attained, thereafter in heaven;
divyan devabhogan = divine pleasures of gods;
asnanti = enjoy.
The word trai-vidyah refers to the three Vedas, Sama, Yajur and Rg.
A brahmana who has studied these three Vedas is called a tri-vedi.
Anyone who is very much attached to knowledge derived from these three Vedas is respected in society.
Unfortunately, there are many great scholars of the Vedas who do not know the ultimate purport of studying them.
Therefore Krishna herein declares Himself to be the ultimate goal for the tri-vedis.
Previously Lord Krishna has illustrated the respective repercussions concerning the nature of the non-believers and the demoniac who are opposed to divinity and everything godly.
Later it could be understood from that description that the Supreme Lord's grace only flows to the mahatmanas or great beings who have dedicated themselves to incessantly acquiring knowledge about Him and are only interested in performing bhakti or loving devotion to Him.
Now in this verse and the next He presents the rewards for those who are not devotees but are not opposed to divinity and who follow karma-kanda or performing meritorious actions for the sake of reaping heavenly rewards.
Such votaries hankering for entry to Swargaloka or the celestial realms to enjoy exquisite heavenly delights worshipping the demigods as prescribed in the three Vedas.
This is what is known as trai- vidya and applies to anyone who has self orientated motives for performing the injunctions of the Rig Veda, Sama Veda, Yajur Veda as well as the Atharva Veda.
Such a person is devoted to performing Vedic rituals for personal gain and not as a spiritual practice as enjoined in the Upanisads and other Vedic scriptures.
So they perform worship and adoration to Indra the chief of the demigods and other celestials even lesser than him by such rituals never realising that it is the Supreme Lord Krishna who alone sanctions whatever has been bequeathed.
Still in consequence of being dedicated to performing Vedic rituals they become purged of all sins which are no longer an obstruction for entry into Swargaloka where they receive the full measure of their merits and are rewarded with heavenly pleasures and enjoyments until their accumulated merit has expired.
In summarisation it has been shown in slokam-s 11 and 12 beginning avajananti mam mudha meaning the fools deride the Supreme Lord. People who worship demigods and other lesser gods with the hope of getting quick results do not respect Lord Krishna and regard Him with esteem, thereby the fit into the class of non-devotees as previously described. But in verse 13 beginning mahatmanas tu mam meaning the great devotees of Lord Krishna are being described.
Those who omit in their lifetime to worship and propitiate the Supreme Lord Krishna or any of His authorised avatars or incarnations and expansions as revealed in the Vedic scriptures it is inevitable that they are bound to samsara or unlimited cycles of birth and death perpetually.
Here is stated trai-vidya or the knowers of the Rig, Sama and Yajur Vedas as well as the Atharva Veda are cognisant of the ultimate truth. Because they study to know the knowledge of the ultimate truth and they are devoted to the rituals enjoined and prescribed in the Vedic scriptures.
Worship of the demigods as prescribed in the Vedas is still in fact worshipping the Supreme Lord indirectly as they are His different part and parcels.
Yet by such worship they receive the soma-pah or remnants of such offerings and from this very act are purified of all dross and cleansed from all taint and having accumulation of merit and praying earnestly for access to heaven, as a result of their virtuous deeds they experience excellent, celestial enjoyments of the demigods for a duration of longevity.
To be continued ...