Below is from the chapter 'Amrit' from "Naam or Word" by Kirpal Singh.

AMRIT ... is the elixir of life, or whoever partakes of it gets everlasting life and escapes forever from the otherwise interminable round of births and deaths. The sages and seers wandered in quest of It, but nowhere in the wide world were they able to find It. Is It then a chimera or mirage? The saints in reply have repeatedly said that Amrit is something real and solid. It is the Water of Immortality, which lies hidden and buried within the depths of the soul, encrusted with the dust of ages, and may be delved into even now and rediscovered, if one has the patience to do as he is bidden.

In the scriptures of the various religions we come across references to the sacred Water of Life. The Muslim divines describe It as Aab-Haiwan or Aab-i-Hayat and always suggested Its use to the world-weary pilgrims. It is also called Chasma-i-Kausar. The Hindu scriptures call It Mansarover or the Pool of Nectar (Amritsar), which if tasted would grant life everlasting. In the Vedas we read of It as Soma Ras, which granted Cosmic Awareness or Universal Consciousness to the Rishis and the Munis who partook of It in ages long ago. The saints generally call It Amritsar or the pool or the fount of Nectar. Christ often spoke of It as the Water of Life. 

And let him that is athirst come, and whosoever will,let him take the Water of Life freely. 

Whosoever drinketh of the water that I shall give him
shall never thirst; but the water that I shall give him
shall be in him a well of water springing up into everlasting life.
— CHRIST

The Rishis and Munis or the holy men of old and even the saints in comparatively recent times tasted of the Water of Life and made their followers drink from the great fountainhead, and it is possible even today to partake of this Water with the grace and kindness of some Master-saint.

From a careful study of the scriptures, we learn that the Water of Life or the Nectar is nothing but the Word or Logos of Christ; Naam or Shabd of the saints; Kalma of the Muslims; and Nad of the Vedic Rishis.

Amrit is the True Naam (or Word),
But It cannot be described in words.
He who tastes of it by attuning with the Word is accepted at His Court.
— AMAR DAS

The Limitless Song (Anhad Bani) has an ambrosial effect,
It lulls both the body and the mind to a quiet repose.
— ARJAN

Those who are proud of Thy Naam are completely saturated with it,
O Nanak! there is but one Amrit (Nectar) and none besides It.
— ANGAD

The Naam of Hari is the elixir and a draught of It makes one contented.
O Nanak! he who drinks of It escapes all delusion.
— AMAR DAS

The Word of the Master is extremely sweet,
Such an elixir one finds within,
Whosoever tastes of It, gets perfected,
O Nanak! such a one remains in perpetual bliss.
— NANAK

Amrit is often used for Hari (God), Hari Kirtan (the Divine Song) and Maha Ras (exhilarating vintage). He alone gets out of desires who engages in the Word. Had is the fruit of the Tree of Life (Amrit-phal) and is a gift from God.

False are all the designs and colors that we see,
A drop of the Water of Life is a blessing that comes from a Sadhu.
— ARJAN

Had Naam alone is Amrit; commune ye with It through the grace of a Master,
Hari Naam is All-pure; a contact with It ends pain and sorrow.
— RAM DAS

A rare soul drinks the cup of divine vintage (Hari Ras),
O Nanak, he gets the reward of the Divine Word and thereafter lives by It.
— ARJAN

I sacrifice my all on Him, who implanted the life-giving Naam in me,
The ambrosia of Naam is supremely sweet,
One drinks of It by the direction and Will of the Master.
— AMAR DAS

The scriptures tell us that what we call Amrit or the Water of Life is just the same thing as Naam or the Word. A touch with this divine vintage gives God-intoxication: 

In this age of Kali Yuga, there is no other Wine but of Amrit.
God's Naam is Amrit in the present Kali age,
This wealth one may get by devotion to a Sadhu.
— ARJAN

Amrit is Sound Principle

Amrit is Divine Harmony, and is reverberating all the time everywhere. It is the Bread of Life (Manna or Heavenly Food) on which the spirit feeds and thrives.

With the meeting of the Satguru, the ever-restless mind gets steady
and one finds the tenth door.
There the Melody divine---the Bread of Life---holds the universe light,
Countless are the strains and endless, ever saturated in Truth,
O Nanak! the contact thereto comes through a God-man alone,
No more the wild goose chase, for Homeward one is led.
— AMAR DAS

A disciplined soul makes one self-disciplined and contented he becomes,
Absorption in the Master awakens the inner Music of the soul;
By drinking the Nectar divine, one is contented and rises in His Presence,
Listen ye to the great Music of the harp and taste It night and day,
A rare soul alone understands It through the Master's grace.
—  NANAK

Amrit is Light Principle

The vision-center behind and between the two eyes, if and when directed steadily toward Gagan (inner horizon), gradually gets lighted up. It starts with flashes as from lightning and in course of time makes manifest a starry sky, and the Sun and the Moon come to view besides several other lighted scenes. When the spirit transcends all these and enters Trikuti, the headquarters of the subtle region, there she beholds the Sun of Brahmand and beyond Brahmand, the Moon of Par Brahmand Region. We come across frequent references to the higher spiritual phenomena in the writings of Sant Tulsi Sahib and many others.

Blessed indeed is the Ambrosial Sound of God, the contact whereof
comes through the grace of the Master;
The darkness is dispelled and one gets enlightenment just as the Sun
chases away the darkness of the night;
Then one sees the otherwise Invisible, the Inexpressible and the Unfathomable One,
as explained by the Master.
— RAM DAS

Wondrous sweet is the Nectarean Voice of the Master,
Fortune may favor a rare soul to relish It.
Light within, one quaffs the quintessence Divine,
And hears the True Sound at the seat of the soul.
— AMAR DAS

Pure is the Light and Soma Juice is the Word,
A contact with them grants a selfless life of everlasting bliss.
— ARJAN

For God, who commanded the light to shine out of darkness, hath shined in our hearts,
to give the light of the knowledge of the glory of God in the face of Jesus Christ.
—  ST. PAUL

Thy Word is a Lamp unto my feet, and a Light unto my Path.
— THE PSALMS

Amrit: Its location

The divine ambrosia can be had by inversion and not anywhere in the world outside. One can find It only if one transcends into the spiritual regions above the physical body. A draught of the Water of Immortality is enough to grant life everlasting to the individual. In order to reach the Hauz-i-Kausar or the pool of nectar, one has to dig deep into the human self.

The human body is the temple of God wherein dwell both the soul and the Over-soul. This temple has quite a number of instruments through which the Self within works in the physical plane without. These instruments may be likened to doors and windows through which the soul and the mind go out into the world in search of worldly pleasures. But the soul itself is imprisoned in the body and knows no way to escape therefrom. The body has nine visible portals: two eyes, two ears, two nostrils, mouth, rectum and the generative organ. So long as the spirit remains absorbed in the sensory pleasures, it cannot have an access to the Heavenly regions and, therefore, cannot taste the elixir of life. Besides these nine outlets there is a hidden spring-door behind the center of the eyes. When the spirit, by means of concentration, is gathered up at this center, it becomes qualified for ingress into higher realms with all the spiritual heritage therein.

The nine portals lead to naught--nectar may be sipped at the tenth.
The Master manifests the Water of Life at the tenth gate,
And listening to the Divine Music, one is led to stillness absolute.
— RAM DAS

There is hardly any need now to search without,
when the Master has shown the Reality within;
The Unending Music swells in the tenth chamber,
there one realizes the ambrosial Word.
— ARJAN

The nectar of Divine Harmony is in the human body, and whoever delves for It, gets It within. All outer activities on the plane of the senses, like pilgrimages, penances and fasts, rites and rituals, forms and formularies, are of no avail. In this Path, one has to lose himself before he can rediscover himself.

It means that one can have life eternal only when one learns and practices the art and science of death-in-life by rising above the body-consciousness at will. This is the only Way to get the Water of Immortality and there is none besides it.

The Naam or the Word is the bestower of all gifts,
And It ever abides in the human body.
— ARJAN

Everyone is endowed with the Water of Life,
None but the destined one can drink It.
— KABIR

The fountain of Amrit is bubbling over,
One can have a taste of It through the Word of God.

Like musk in the deer is hid the nectar within,
And like the deer a mad search is made without.
— AMAR DAS

A Sufi saint says,

Beloved is in the house and I make a search in the world, With a spring of crystal water within, I go athirst.

Inside the head, there is an inverted well with an opening behind the eyes. A current of nectar issuing forth from the well is coming into the body; but the unfortunate spirit, ever busy in the outer pursuits of the world, is not destined to have a taste of It and so continues in sorrow.

Everything of any value is in the body and nothing is without. Whoever has, through the grace of the Master, found the treasures within, is indeed blessed and enjoys true happiness both within and without. He drinks the ambrosial showers as they fall and is ever in a state of blissful intoxication. The Way to It, however, lies through some Master-saint, and the spirit, torn away from her source ever since the day of creation, is once again reconciled with her Creator and lives in perpetual peace and beatitude.

Everything is within and nothing without,
He who searches without is yet in ignorance.
He who finds it within himself through a Master-soul,
Ever lives in a state of bliss and beatitude.
The Amrit falls down in a big shower,
Night and day he lives in perfect satiety,
And sings the praises of God.
The aeons of separation come to an end,
And the blighted tree once again blossoms forth.
Gifted with right knowledge, he revels in Naam,
All hail to the Master! that brought this about.
— ARJAN

The pool of nectar lies in the folds of the mind; it is only when the mind grows still that it becomes manifest. A contact with Naam grants eternal life. O Nanak! drink within the elixir of life as a pure gift of the Guru,
He alone takes in the divine drink, who is destined from above.
— ANGAD

The mind must first be purged of all ills, before one can receive the life-giving ambrosia. Through instructions of the Master, the mind becomes pure,
And then the sacred pool comes to view.
— AMAR DAS

Who can taste this Nectar 

From the writings of the Masters it appears that one cannot taste this nectar until one learns to die while alive. One has, therefore, to "forsake the flesh for the spirit'' for "flesh and blood cannot inherit the Kingdom of God."

If any man will come after me, let him deny himself,
And take up his cross daily and follow me.
For whosoever will save his life shall lose it,
But whosoever will lose his life for my sake, the same shall save it.
— CHRIST

We have been leading a physical existence only. We know how to live on the physical plane and that we do with the help of our physical senses. We have never known that there is anything beyond and that we have senses subtle and causal, apart from the physical, and can make use of them by transcending the physical plane. There are tremendous possibilities in man, fashioned as he is in the image of God, but alas! in the mighty swirl of mind and matter we have lost hold of the lifeline within and are drifting headlong in the stream of life with no anchorage. A Master-saint is the only refuge and a haven where one may for a while have a respite and time to think over his sad plight. And how does the Master help here ? He shows one how to leave the body by withdrawing the sensory currents at the seat of the soul. This transcension of the physical body is called "death-in-life." It is the Open Sesame that unlocks the door leading into the Kingdom of God.

If thou wishest to have everlasting life,
Learn thou to die in the body, before death overtakes thee.
— MAULANA RUMI

He who knows how to die while living drinks Amrit (the Water of Life),
My mind is convinced of the need and is devoted to the Master's instructions.
— RAM DAS

Learn to die while alive, for in the end death over-takes all.
— BABA FARID

Learn how to die that you may begin to live.
— THOMAS A KEMPIS

Drink ye the Water of Life---a pure gift from the Master,
With an easy death, ye shall rise in eternal life.
— NANAK

Spiritual Comfort is God's free gift and not of our own merit. It comes only through the grace of some Godman. He is the "Way, the Truth, and the Life." The absorption in the Master alone helps one to gain the pool of nectar within and this is called a second birth or resurrection.

Above is from the chapter 'Amrit' from "Naam or Word" by Kirpal Singh.