Also see:

Ramana Maharshi: how to abide as the Self

Shankara: How to Meditate for Self-Realisation

Shankara: How to realise the Self (Brihadaranyaka Upanishad Commentary)

The entire path explained: the Path of Sri Ramana

Turn Within? Really? Isn’t this dualistic and doesn’t this just strengthen the ego?

If God is everywhere, why do we have to turn within? Why can’t we see God in the World? Sri Ramana Maharshi

Here is what the Vedanta scriptures, such as the Upanishads and the writings of Sri Shankara and Sri Gaudapada say, together with quotes from Sri Ramana Maharshi:

The Lord created the senses out-going: therefore, one sees outside and not the Self within. Some intelligent man, with his senses turned away (from their objects), desirous of immortality, sees the Self within.
~ Katha Upanishad 2.1.1

In his commentary on this above verse (Katha Upanishad 2.1.1), Shankara writes:

‘…the perceiver sees the external objects which are not-Self/not the Atman, such as sound, etc., and not the Self within. Though this is the nature of the world, some (rare) discerning man, like turning back/ reversing the current of a river, sees the Self within…The group of sense organs, beginning with the ear, should be turned away from all sense-objects. Such a one, who is purified thus, sees the indwelling self. For it is not possible for the same person to be engaged in the thought of sense-objects and to have the vision of the Self as well.‘

Dwelling on external objects will only increase evil propensities, so wisely recognising this fact, one should abandon external objects and and constantly attend to one’s true nature within, the Atman [the Self].
~ Shankara, Vivekachudamani

(Note, there are so many quotes from Shankara’s Vivekachudamani which advocate turning within/away from objects that they would ovewhelm this post, but you can find some of these quotes compiled together here in a separate post.)

The knot of the ignorance in the heart is broken completely only when one sees his Self as secondless through Nirvikalpa Samadhi

~Adhyatama Upanishad 1.17

By expelling (from the mind) without any remainder all objects which are superimposed on one’s Atma, one becomes himself Parabrahman the full, the secondless and the actionless

~Adhyatma Upanishad 1.21

Turiya is not that which is conscious of the inner (subjective) world, nor that which is conscious of the outer (objective) world, nor that which is conscious of both…It is the cessation of all phenomena…This is what is known as the Fourth (Turiya). This is Atman and this has to be realised. ~Mandukya Upanishad

In Shankara’s commentary on the Mandukya Upanishad, in his introduction to the text he writes:

Just as the normal state of a man, afflicted by disease, consists in his getting cured of the disease, similarly the normalcy of the Self, stricken with identification with misery, is regained through the cessation of the phenomenal universe of duality…since the phenomenal world of duality is a creation of ignorance, it can be eradicated through knowledge…

In his commentary on Katha Upanishad verse 1.2.20 Sri Shankara writes:

‘…One whose intellect has been withdrawn from all objects, gross and subtle, when this takes place, this is known as ‘inactivity of the sense organs’. Though this ‘inactivity of the sense organs’ one sees that glory of the Self. ‘Sees’ means he directly realises the Self as ‘I am the Self’ as thereby becomes free from suffering’

When the mind…remains unshakable and does not give rise to appearances, it verily becomes Brahman.
~ Gaudapada, Mandukya Upanishad Karika

When the mind, after realizing the knowledge that Atman alone is real, becomes free from imaginations and therefore does not cognize anything, for want of objects to be cognized, it ceases to be the mind.
~ Gaudapada, Mandukya Upanishad Karika

The mind severed from all connection with sensual objects, and prevented from functioning out, awakes into the light of the heart, and finds the highest condition. The mind should be prevented from functioning, until it dissolves itself in the heart. This is Jnana, this is Dhyana, the rest is all mere concoction of untruth.
~ Amritabindu Upanishad

As long as the objective universe is perceived one does not realise the Self.
~ Yoga Vasishta

The Self (Atman) is beyond all expression by words beyond all acts of mind; It is absolutely peaceful, it is eternal effulgence free from activity and fear and it is attainable by Samadhi
~ Gaudapada, Mandukya Upanishad Karika 3.37

Shankara’s commentary from the above verse from Gaudapada 3.37 states:

…The Self (Atman) is denoted by the word Samadhi as it can be realised only by the knowledge arising out of the deepest concentration (on its essence), Samadhi. Or the Self (Atman) is denoted by Samadhi because it is the object of concentration, the Jiva concentrates his mind on the Self (Atman)…

In the next verse Gaudapada writes in verse 3.38 of his Mandukya Karika:

There can be no acceptance or rejection where all mentation stops. Then knowledge is established in the Self and is unborn, and it becomes homogenous

Shankara’s commentary on this verse 3.38 is as follows:

…therefore there is no rejection or acceptance in It, where thought does not exist. That is to say, how can there be rejection or acceptance where no mentation is possible in the absence of the mind? As soon as there comes the realisation of the Truth that is the Self, then, in the absence of any object, knowledge (Jnanam) is established in the Self, like the heat of fire in fire. It is then birthless (ajati) and becomes homogenous.

In his commentary on the Katha Upanishad, verse 2.1.2, Shankara writes:

‘The natural tendency to see external objects, which are not-Self, is the cause of ignorance, the obstacle to the realisation of the Self. The desire of external/outward enjoyments pertaining to this world and the next, which are presented by ignorance, is another obstacle. The realisation of the Self being impeded by these two, ignorance and desire, men with little intelligence pursue only external objects of desire….This being so, the intelligent, knowing the certain immortality of concentration in the inner Self…

When the five organs of perception become still, together with the mind, and the intellect ceases to be active: that is called the Supreme State [Brahma-Vidya or Self Knowledge]
~Katha Upanishad 2.3.10

Shankara’s commentary on this above verse (Katha Upanishad, verse 2.3.10) states the following:

‘At the time when the five senses…, together with the mind…, which is now no longer functioning and thinking, are at rest in the Self alone, after turning away from objects, and with the intellect…no longer engaging with its functioning, that they call the highest state [Brahma-Vidya or Self-Knowledge].’

That which is not seen, though within us, is called the eternal and indestructible Self.
~ Yoga Vasishta

After knowing that by which you know this world, turn the mind inward, and then you will realise the effulgence of the Self.
~ Yoga Vasishta

Strenuously withdrawing all thoughts from sense objects, one should remain fixed in steady, non-objective [ie. subjective] enquiry. This, in brief, is the means of knowing one’s own real nature; this effort alone bring about the sublime inner vision.
~ Sri Ramana Maharshi, Sri Ramana Gita

If, on the contrary, you withdraw your mind completely from the world and turn it within and abide thus, that is, if you keep awake always to the Self, which is the substratum of all experience, you will find the world, of which alone you are now aware, just as unreal as the world in which you lived in your dream.
~ Sri Ramana Maharshi, Maharshi’s Gospel

So long as all objects are not renounced, the Self is not won. What remains after the renunciation of the entire objective manifold is said to be the Self. Therefore, in order to realize the Self, renounce everything. Having cast off all (objects), assimilate yourself to that which remains.

~ Annapurna Upanishad 1.45-1.46

Q. When will the realization of the Self be gained?
Sri Ramana: When the world which is what-is-seen [ie. objects] has been removed, there will be realization of the Self which is the seer.
Q. Will there not be realization of the Self even while the world is there?
Sri Ramana: There will not be.
~ Sri Ramana Maharshi, Who Am I?

When the mind, which is the cause of all cognition’s and of all actions, becomes quiescent, the world will disappear…All the texts say that in order to gain release one should render the mind quiescent; therefore teaching is that the mind should be rendered quiescent.
~ Sri Ramana Maharshi, Who Am I?

Therefore, when the world appears, the Self does not appear; and when the Self appears the world does not appear.
~ Sri Ramana Maharshi, Who Am I?

When the mind comes out of the Self, the world appears.
~ Sri Ramana Maharshi, Who Am I?

When the mind that is subtle goes out through the brain and the sense organs, the gross names and forms appear; when it stays in the heart, the names and forms disappear. Not letting the mind go out, but retaining it in the Heart is what is called “inwardness” (antarmukha). Letting the mind go out of the Heart is known as “externalisation” (bahir-mukha). Thus, when the mind stays in the Heart, the ‘I’ which is the source of all thoughts will go, and the Self which ever exists will shine.
~ Sri Ramana Maharshi, Who Am I?

Desirelessness is wisdom. The two are not different; they are the same. Desirelessness is refraining from turning the mind towards any object. Wisdom [Jnana] means the appearance of no object.
~ Sri Ramana Maharshi, Who Am I?

Q. How long should inquiry be practised?
Sri Ramana Maharshi: As long as there are impressions of objects in the mind, so long the inquiry “Who am I?” is required
~ Sri Ramana Maharshi, Who Am I?

According to Sri Ramana Ashram, the text Guru Vachaka Kovai ‘provides the most precise, systematic and authoritative exposition of Sri Bhagavan’s [Ramana Maharshi’s] teaching‘, and here is a definitive teaching given in verse 291:

291. If one wants to be saved, one is given the following true and essential advice: just as the tortoise draws all its five limbs within its shell, so one should draw the five senses within and turn one’s mind Selfward. This alone is happiness.

Compare with Bhagavad Gita 2.58:

‘One who is able to fully withdraw the senses from their objects, just as a tortoise withdraws its limbs into its shell, is established in Divine Knowledge’.

Here, once again, the method to attain Self-Realisation, which is perfect infinite eternal Happiness, is made clear by Sri Ramana Maharshi in verse 293 of Guru Vachaka Kovai:

293. Having known for certain that everything which is seen, without the least exception, is merely a dream, and that it [the seen] does not exist without the seer, turn only towards Self – Sat-Chit-Ananda – without attending to the world of names and forms, which is only a mental conception.

Also see: The Essential Teachings of Sri Ramana Maharshi: how to abide as the Self, the world is not real, attend to yourself