Truth as perceived by Seers have been transmitted orally.
Such experience was gained by Seers by following Vedas.
Vedas are expressions of Reality.
Being Personal experiences,they can not be classified at the time of transmission.
Thousands of Seers,called Rishis,have transmitted the information.
Such experiences,as time grew became voluminous.
After a period of time these experiences have come to be classified.
One must understand that experiences are unique and can not be replicated by the others.
Yet it may serve as signpost for Seekers.
Each individual in unique.
Their dispositions vary.
Realisation is dependent on One’s nature,Swabhava.
As many number of people,as many experiences.
When they are studied four general directions may found to Realize Self, Brahman.
Gnana Yoga Path of Knowledge,
Karma Yoga Path of Action,
Raja Yoga, Path of regulation of Consciousness by Physical and mental approach and
Karma Yoga, Path of Action,by performing an Action without being clouded by its results.
These paths are found in all Hindu texts.
There is no separate text for each of these.
Even Patanjali Yoga Sutra contains details of other Path,though it concentrates on Raja Yoga.
Thus, one will find all these in Bhagavad-Gita and all Vedic texts.
It is for us to choose the Path.
To guide us dispassionately,a Guru is needed.
One would find such instances of all paths even among the specific Mantras for A Deity.
Though Vedas do not advocate personal Concept of God and insists on Reality beyond Attributes,called Nirguna Aradhana, Vedas, understanding that human mind needs an anchor to evolve Spiritually,have also provided for Saguna Aradhana,that is Realising Reality through Deities.
Many stotras are found in many Deities.
All mantras,Astototras, Sahasranamas,though addressed to Individual Deity,also contain mantras on Nirguna Brahman.
In some texts it is marked clearly
For example, Lalitha Sahasranama.
You would find Saguna Upasana and Nirguna Upasana,and the Union of SelfandBrahman,Eikyanusanthaana,marked.
If we look, all Yoga systems are also covered.
Here let me address the Karma Yoga being mentioned in Individual Sahasranama.
Vak Yagnyena Kalpatham,
Mano Yagnena kalpatham’
Sakshur Yagnena Kalpatham,
Srothram Yagnena Kalpatham
Atma Yagnena Kalpathaam,
Yagnyo Yagnena Kalpathaam ‘
(Sri Rudram-Chamaka Prasna)
Please read Details on Vedic Rites
Here the fruits of Action performed in Yagnyas is dedicated to the Reality,by even relinquishing the results of Yagnyas to Yagnya Itself.
The meaning of the lines quoted above is,
‘I dedicate Speech to Yagnya,
Mind to Yagnya,
Perception to Yagnya,
Hearing, knowledge to Yagnya.
Self to Yagnya and
Yagnya,action to Yagnya.
Clear indication here of The Performance,Performer and for Whom it is performed are One.
You will find the echo when Krishna says to Arjuna in the Bhagavad-Gita,
Real Karma Yoga is devoid of the even the thought,Determination,Sankalpa, Results.