Dhyana, is the Sanskrit term for meditation used in Hinduism. Vedanta is a philosophy of Self-realization, and its practice is a way of Self-realization through yoga and meditation.
Shvetashvatara Upanishad Page -47-50 – Tells us about Right place , Right posture and other essentials one should do before meditation like Pranayama.
The right posture -:
त्रिरुन्नतं स्थाप्य समं शरीरं हृदीन्द्रियाणि मनसा संनिवेश्य |
ब्रह्मोडुपेन प्रतरेत विद्वान् स्त्रोतांसि सर्वाणि भयावहानि ||8||
Placing the body in straight posture , holding the chest throat and
head erect , and drawing the senses and the mind into the heart , the
knowing one should cross over all the fearful currents by means of
raft of Brahman.
This verse tells us about the right posture in which one should be for
practicing both Pranayama and Dhyana (meditation).
प्राणान्प्रपीड्येह संयुक्तचेष्ट: क्षीणे प्राणे नासिकयोच्छवसीत |
दृष्टाश्वयुक्तमिव वाहमेनं विद्वान्मनो धरयेताप्रमत्त: ||9||
Controlling the senses with an effort , and regulating the activities
in the body one should breathe out with nostrils when the vital
activities become gentle . Then the knowing one , without being in the
least distracted should keep his hold on mind as the reins attached to
restive horses.
This verses is telling us the importance of pranayama before
starting of meditation. Because its believed that better mental
stability and concentration can be achieved through Pranayama , which
is essential for Dhyana or Mediation . So its recommended to practice
Pranayama before starting meditation in Shankkara bhashya of this
Upanishad.
The right place - :
समे शुचौ शर्करवहिनवालुका-विवर्जिते शब्दजलाश्रयादिभि : |
मनोSनुकुले
न तु चक्षुपीडने गृहानिवाताश्रयणे प्रयोजयेत् ||१०||
One should perform one’s exercises in concentration resorting to the caves and such other pure places helpful to its practice –Place
where ground is level without pebbles and scenery pleasing to the eyes
; when there is no wind ,dust, fire ,dampness , disturbing noises.
The Mundaka Upanishad Verse 2.2.6 tells us the way of doing meditation.
अरा इव रथनाभौ संहता यत्र नाड्यः स एषोऽन्तश्चरते बहुधा जायमानः ।
ओमित्येवं ध्यायथ आत्मानं स्वस्ति वः पाराय तमसः परस्तात् ॥ ६ ॥
arā iva rathanābhau saṃhatā yatra nāḍyaḥ sa eṣo'ntaścarate bahudhā
jāyamānaḥ |
omityevaṃ dhyāyatha ātmānaṃ svasti vaḥ pārāya tamasaḥ
parastāt || 6 ||
6 Where the nerves of the body meet together as the spokes in the nave
of a wheel, this Atman is within it variously horn; meditate upon
“Om” as the Atman. May there be no obstacle to your going to the
other side beyond darkness.
Chandogya Upanishad 1.1 -Page No- 5 -tells us that one should meditate upon the syllabus Om. We also find more description regarding meditation in next verses of this Upanishad.
In
Maitri Upanishad this meditation techniques are also described in very detail.
- And thus it has been said elsewhere: The artery, called Sushumna, going upwards (from the heart to the Brahmarandhra), serving as the
passage of the Prana, is divided within the palate. Through that
artery, when it has been joined by the breath (held in subjection), by
the sacred syllable Om, and by the mind (absorbed in the contemplation
of Brahman), let him proceed upwards, and after turning the tip of the
tongue to the palate, without using any of the organs of sense, let
greatness perceive greatness. From thence he goes to selflessness, and
through selflessness he ceases to be an enjoyer of pleasure and pain,
he obtains aloneness (kevalatva, final deliverance). And thus it is
said:
'Having successively fixed the breath, after it had been restrained, in the palate, thence having crossed the limit (the life),
let him join himself afterwards to the limitless (Brahman) in the
crown of the head.'
- And thus it has been said elsewhere: Two Brahmans have to be meditated on, the word and the non-word. By the word alone is the
non-word revealed. Now there is the word Om. Moving upward by it
(where all words and all what is meant by them ceases), he arrives at
absorption in the non-word (Brahman). This is the way, this is the
immortal, this is union, and this is bliss. And as the spider, moving
upward by the thread, gains free space, thus also he who meditates,
moving upward by the syllable OM, gains independence. Other teachers
of the word (as Brahman) think otherwise. They listen to the sound of
the ether within the heart while they stop the ears with the thumbs.
They compare it to seven noises, like rivers, like a bell, like a
brazen vessel, like the wheels of a carriage, like the croaking of
frogs, like rain, and as if a man speaks in a cavern. Having passed
beyond this variously apprehended sound, and having settled in the
supreme, soundless (non-word), unmanifested Brahman, they become
undistinguished and undistinguishable, as various flavours of the
flowers are lost in the taste of honey. And thus it is said: 'Two
Brahmans are to be known, the word-Brahman and the highest Brahman; he
who is perfect in the word-Brahman attains the highest Brahman.' 23.
And thus it has been said elsewhere: The syllable Om is what is called
the word. And its end is the silent, the soundless, fearless,
sorrowless, joyful, satisfied, firm, unwavering, immortal, immovable,
certain (Brahman), called Vishnu. Let him worship these two, that he
may obtain what is higher than everything (final deliverance). For
thus it is said:
Essene of above verses – Contemplation upon Om by allowing the mind
to follow the breath that travels upward along the Susumna Nadi (Nerve
Strand ) into head region where the top most chakra is located .
Meditate upon the Shabda Brahman chanting OM and meditation upon
Ashabda Brahman (non sound ) with complete silence . Concentration and
meditation upon the space in the heart which is the physical location
of the self in the body. -
The meditation techniques are also described in Puranas for instance Shreemad Bhagvat purana. SB 11.14: Lord Kṛṣṇa Explains the Yoga System to Śrī Uddhava.
सम आसन आसीनः समकायो यथासुखम्
हस्तावुत्सङ्ग आधाय
स्वनासाग्रकृतेक्षणः ॥32॥
प्राणस्य शोधयेन्मार्गं पूरकुम्भकरेचकैः
|
विपर्ययेणापि शनैरभ्यसेन्निर्जितेन्द्रियः ॥33||
sama āsana āsīnaḥ sama-kāyo yathā-sukham
hastāv utsańga ādhāya
sva-nāsāgra-kṛtekṣaṇaḥ
prāṇasya śodhayen mārgaḿ
pūra-kumbhaka-recakaiḥ
viparyayeṇāpi śanair abhyasen
nirjitendriyaḥ
The Supreme Personality of Godhead said: Sitting on a level seat
that is not too high or too low, keeping the body straight and
erect yet comfortable, placing the two hands on one’s lap and focusing
the eyes on the tip of one’s nose, one should purify the pathways of
breathing by practicing the mechanical exercises of pūraka, kumbhaka
and recaka, and then one should reverse the procedure (recaka,
kumbhaka, pūraka). Having fully controlled the senses, one may thus
practice prāṇāyāma step by step.SB 11.14.32-33
हृद्यविच्छिनमोङ्कारं घण्टानादं बिसोर्णवत्|
प्राणेनोदीर्य तत्राथ
पुनः संवेशयेत्स्वरम् ॥34||
hṛdy avicchinam oḿkāraḿ ghaṇṭā-nādaḿ bisorṇa-vat
prāṇenodīrya tatrātha punaḥ saḿveśayet svaram
Beginning from the mūlādhāra-cakra, one should move the life air
continuously upward like the fibers in the lotus stalk until one
reaches the heart, where the sacred syllable om is situated like the
sound of a bell. One should thus continue raising the sacred syllable
upward the distance of twelve aṅgulas, and there the oṁkāra should be
joined together with the fifteen vibrations produced with
anusvāra.SB 11.14.34
हृत्पुण्डरीकमन्तःस्थमूर्ध्वनालमधोमुखम्
ध्यात्वोर्ध्वमुखमुन्निद्रमष्टपत्रं सकर्णिकम् ॥ 36||
hṛt-puṇḍarīkam antaḥ-stham ūrdhva-nālam adho-mukham
dhyātvordhva-mukham unnidram aṣṭa-patraḿ sa-karṇikam
Keeping the eyes half closed and fixed on the tip of one’s nose, being enlivened and alert, one should meditate on the lotus flower
situated within the heart. This lotus has eight petals and is
situated on an erect lotus stalk. One should meditate on the sun, moon
and fire, placing them one after the other within the whorl of that
lotus flower. SB 11.14.36-42
Vedanta recommends regular meditation for everyone, particularly during the hour or two before dawn, which it calls Brahma Muhurta or the hour of God. Sunrise and sunset are other important times for meditation because at these transitional periods in nature, energy can be more easily transformed. The times of the new, full and half moons are also excellent, as are the solstice and equinoctial points.
The above things can be found in Adi Shankaracharya’s commentary on Shvetashvatara Upanishad.