The famous verse of geeta is delivered as an upadesha which says arjuna that vedas are subject of trigunas and hence he should go beyond vedas i.e trigunas.
त्रैगुण्यविषया वेदा निस्त्रैगुण्यो भवार्जुन | निर्द्वन्द्वो नित्यसत्वस्थो निर्योगक्षेम आत्मवान्
Now we know that vedas are brahma vishaya indeed because it talks about brahman and god etc.
In many places veda is synonymous with brahman
Why then BG asks to overcome or renounce the vedas ?
Is there anything beyond veda vishaya?
First of all, here is what Krishna says about the Vedas in chapter 2 of the Bhagavad Gita:
42-43. Men of small knowledge are very much attached to the flowery words of the Vedas, which recommend various fruitive activities for elevation to heavenly planets, resultant good birth, power, and so forth. Being desirous of sense gratification and opulent life, they say that there is nothing more than this. 44. In the minds of those who are too attached to sense enjoyment and material opulence, and who are bewildered by such things, the resolute determination for devotional service to the Supreme Lord does not take place. 45. The Vedas deal mainly with the subject of the three modes of material nature. O Arjuna, become transcendental to these three modes. Be free from all dualities and from all anxieties for gain and safety, and be established in the self. 46. All purposes served by a small well can at once be served by a great reservoir of water. Similarly, all the purposes of the Vedas can be served to one who knows the purpose behind them. 47. You have a right to perform your prescribed duty, but you are not entitled to the fruits of action. Never consider yourself the cause of the results of your activities, and never be attached to not doing your duty.
The first thing to note is that in verses 42-43, Krishna is not condemning the Vedas, but the Purva Mimamsa school, i.e. those who are focused on the Karma Kanda of the Vedas to the exclusion of the Jnana Kanda. Here is what Adi Shankaracharya says in his commentary on these verses:
[W]ho are they? they are — avipascitah, people who are undiscerning, of poor intellect, i.e. non-discriminating; veda-vada-ratah, who remain engrossed in the utterances of the Vedas, in the Vedic sentences which reveal many panegyrics, fruits of action and their means; and vadinah, who declare, are apt to say; iti, that; na anyat, nothing else [God, Liberation, etc.]; asti, exists, apart from the rites and duties conducive to such results as attainment of heaven etc.
And here is what Ramanujacharya says:
They rejoice in the letter of the Vedas i.e., they are attached to heaven and such other results (promised in the Karma-kanda of the Vedas). They say that there is nothing else, owing to their intense attachment to these results. They say that there is no fruit superior to heaven etc. They are full of worldly desires and their minds are highly attached to secular desires.
But you asked about verse 45. That verse is not saying that the Vedas are limited to the Gunas of Prakriti, but rather that for those who have a mixture of Gunas, the Vedas have information relevant to them, not that it only has such information. Here is what Adi Shankaracharya says in his commentary on this verse:
To those who are thus devoid of discriminating wisdom, who indulge in pleasure, O Arjuna, vedah, the Vedas; traigunya-visayah, have the three qualities as their object, have the three gunas, i.e. the worldly life, as the object to be revealed.
And here is what Ramanujacharya says:
The word Traigunya means the three Gunas — Sattva, Rajas and Tamas. Here the term Traigunya denotes persons in whom Sattva, Rajas and Tamas are in abundance. The Vedas in prescribing desire-oriented rituals (Kamya-karmas) have such persons in view. Because of their great love, the Vedas teach what is good to those in whom Tamas, Rajas and Sattva preponderate. If the Vedas had not explained to these persons the means for the attainment of heaven etc., according to the Gunas, then those persons who are not interested in liberation owing to absence of Sattva and preponderance of Rajas and Tamas in them, would get completely lost amidst what should not be resorted to, without knowing the means for attaining the results they desire. Hence the Vedas are concerned with the Gunas.
And for good measure, the Kashmiri Shaivite Acharya Abhinavagupta also agrees that this Gita verse does not condemn the Vedas in any way:
Traigunya-etc. The Vedas bind very much [only] by means of the three Strands and they do not bind on their own accord. For, the rituals prescribed in the Vedas, create bondage if they are performed with an intention of pleasure, or of (avoiding) pain, or with an illlusion of attachment. Hence the traid of Strands in the form of desire (or in a pleasing form) must be abandoned. If the present passage were intended to condemn the Vedas, then the act of fighting the battle in question would be spoiled, because there is nothing other than the Vedas do not bind those, from whom the desire for fruit has completely gone. Because the Vedas alone are useful for proper knowledge in the case of those persons [free from the Strands] hence [the Lord] says [verse 2.46].
Answer: Doership -- is what makes Vedas as scoped to 3 modes.
Translation:
BG 2.45 - Veda-s are subjected to 3 modes of material nature (Sattva, Rajas, Tamas); O Arjuna, become free of these 3 modes, free of duality, ever situated in "constant-ness"; free of gaining support [and] self sustained
Comparing Vedas (public domain) and Gita (private domain), is like comparing apple and oranges! They are Not competitors.
Veda-s and many subsequent philosophies derived from it, assumes "Doership". i.e. they provide iterative teachings about Dharma (do-able), Adharma (non-doable), rituals, Karma-s and all such aspects.
While Gita refutes "doership". It says that the 3 modes are responsible for any Karma happening. One doesn't dictate, what Karma he/she will do.
BG 3.27 — All actions (karma-s) are enacted in Prakruti by [3] modes (guna-s). Bewildered with identity, the self(Atma) believes "'I' am the doer".
According to Veda-s, a knowledgeable person may have to follow what is Dharma, which is caused by influence of Sattva and be aware of Rajas (cause of Adharma) and Tamas (cause of Vidharma).
While Gita says that a knowledgeable person knows that he is not the doer! Only 3 modes are acting, by themselves.
BG 5.8, 5.9 — "'I' certainly don't do anything" is thought by knower of elementary (tattva gyAna) - even while seeing, hearing, touching, smelling, eating, moving, dreaming, breathing, talking, discarding, accepting, opening, closing; -- "Senses only are acting in the subjects of senses" - is understood.
Since Veda-s teach that a person "should do this, should not do that", they are limited to 3 modes of nature. In fact, in any plane of world, everything is bound by 3 modes. So Vedas are well placed in their teachings.
Gita doesn't belittle or criticise Vedas. It just says for what purpose Vedas are meant for. However, the supreme nature of Atma is beyond this 3 modes and any purpose.
BG 7.13 — These whole universe being bewildered by the nature of these 3 modes, doesn't know "Me", who is above [them], the transcendental Indivisible (Atman).
Analogy:
If the world (heaven, hell, earth, ...) is some sport, then Vedas are rules of that sport. If you hit like this -- it's foul, if you hit like that -- it's a point, one should play like this, one should maintain decorum, use these instruments, ...
Gita says that the whole sport is spot fixed!
