From the book "Jap Ji – The message of Guru Nanak", written by Sant Kirpal Singh

Christianity

Saint John has stated in his Gospel:

In the beginning was the Word;
and the Word was with God, and the Word was God.
The same was in the beginning with God.
All things were made by Him, and without Him
was not anything made that was made. – St. John I: 1-3

By the Word of the Lord were the heavens made.

Again:

He spoke and it was done. – Psalm 33: 6, 9

Upholding all things by the Word of His Power. – Hebrews 1:3

The grass withereth, the flower fadeth
but the Word of God shall stand forever. – Isaiah 40:8

Forever, O Lord, Thy Word is settled in heaven. – Psalm 119:89

St. Paul said: For the Word of God is quick (living) and powerful and sharper than any two-edged sword, piercing even to the dividing asunder of soul and spirit and of the joints and marrow, and is a discerner of thoughts and interests of heart. – Hebrews 4:12

 

Hinduism

According to the Hindu theological books, the whole creation was made through Nad. They also refer to It as Akash Bani (voice coming down from the Heavens). We have references to It even in the Vedas, the ancient scriptures of the world. We read of It in the Upanishads, as for instance, the Nad Bind Upanishads, which deal with the matter in a very lucid manner. The Hatha Yoga Pradipaka also speaks of this Sound Principle.

He has taken the support of the Word, the melodious Tune. – Chandogya Upanishad

Let Yogi sit on Sidh Asan and while practising the Vaisnavi mudra,
he should hear the Sound through his right ear.
– Nad Bind Upanishad

By communion with the Word he will become deaf to the external sounds,
and will attain the Turiya Pad or a state of equipoise within a fortnight.
– Nad Bind Upanishad

First the murmuring sounds resembling those of the waves of oceans,
the fall of rain and the running rivulets and then Bheri will be heard
intermingled with the sounds of bell and conch, etc.

Madame Blavatsky, the founder of the Theosphical Society, in her book "Voice of the Silence," states that several sounds are heard when holding communion. "The first is like the nightingale's sweet voice, chanting a parting song to its mate. The next, resembles the sound of silver cymbals of the Dhyanis, awakening the twinkling stars. It is followed by plain melodies of the ocean's spirit, imprisoned in the conch shell, which in turn gives place to the chant of Vina. The melodious flute-like symphony is then heard. It changes into a trumpet-blast, vibrating like the dull rumbling of a thunder cloud. The seventh swallows all other sounds. They die and then are heard no more."

Mohammedanism

Among the Muslim Sufis, it is known as Sultan-ul-Azkar, (the king of prayers). Another order of Sufis calls it Saut-i-Sarmadi, (the Divine Song). They also call it Nida-i-Asmani, (the sound coming down from the (Heavens), Kalam-i-Qadim (the ancient sound) and the Kalma or Word. The fourteen regions were made by the Kalma – the Word.

Khawaja Hafiz, a great divine, says:

From the turret of the Heaven a call bids thee Home.
But fallen into the snares thou listeneth not.
No one knows where the Mansion of the Beloved lies,
But sure enough the chiming of the bells proceeds therefrom.

Again:
Take the stop-cock from thy ears,
and hear thou the voice of emancipation, coming to thee.
Attach not to the material world.
The Elixir of life is showering from above.
The beat of love while sounding in the Heavens,
Sounds blessings to the souls of the devotees."

Maulana Rumi, in his Masnavi says:
Grow not skeptical, but attune thyself to the Sound
coming down from the Heavens.
Thy soul shall have revelations from afar.
What are these but glimpses of the Unrevealed:
Were I to speak of these sweet melodies
Even the dead shall rise from their graves.

Again:
Rise above the horizon, O brave soul,
and hear the melodious song coming from the highest heaven.

Prophet Mohammed says:
The Voice of God comes unto my ears as any other sounds.

Shah Niaz, another Muslim devotee, says:
Soul is the Will and the Secret of God. Its meditation is carried without the help of tongue and palate. Alas! thou art stuck fast in the physical bondage and do not hear the Holy Sound of God. My Beloved is speaking to thee all the while, but woe to thee for thou heareth not the Voice.

The whole universe is resounding with the Sound, and thou hast only to open the door of thine ear.

For opening the ear, it is sufficient to stop hearing the outer sounds. If you do this, you will hear the perpetual and unending Sound. It is infinite and has no beginning nor end, and on account of that, it it called Anhad (without any limits). Without this Word – the Eternal Sound- an infinite expression of the Infinite, the world could not have come into existence. Hold communion with the Melodious Sound and lose yourself in it, O wise man.

Kabir Sahib says:
Without the Word, Sound or Eternal Song, the soul sees not. Where could she go?
As she cannot fathom the mystery of the 'Word,' she is wandering from place to place. – Kabir

Mind hankereth after evils; through the Word, the Master restraineth it. – Guru Teg Bahadur

Through the medium of Word, soul doth cross the endless ocean of matter.
Lowly Nanak, therefore, glorifies His Naam (the Word). – Ram Kali M.1

The Word is both earth and ether. These had their being through the Word.
This Word expressed itself in other aspects as well. The whole creation sprang up after the Word.
O Nanak, that endless Word is reverberating in each heart.

The all-pervading Word has attracted all my mind. What else have I to think of?
Communion of the soul with the Word creates everlasting Bliss.
At-one-ment with the Lord procures the Essence of Joy and Peace. – Shri Rag M.1

I am emancipated. The God-Man has un-fettered me.
Through the communion of soul with the Word,
I have gained the resplendent seat of honour:
O Nanak, the all-pervading Naam or the Word dwelleth in the hearts of all.
The company of the Gurmukhs procures communion with It. – Malar M.1

Far off, on the other shore, is my Beloved.
The God-man's Word, alone, carries the soul across.
In the company of saints, man is in clover and never repents. – Tukhari M.1

How can the ignorant get to the principle of union of soul with the Word?
Without communion with the Word, soul comes and goes.
O Nanak, the Gurmukh who is himself emancipated,
meets by the merciful Writ of the Lord. – Maru M.1

The creation and the ultimate dissolution of the universe is caused through the Word.
Again, through Word, it takes its existence anew. – Magh M.3

By good luck, the Lord consort has become ours.
The Endless Song (the Word), resounding everywhere, gives a clue to His Court. – Bilawal M.5

The Word made all the earthly systems. – Gauri M.5

Tulsi Das says:
He is the true Saint, who talks about the secret of the Divine Word (the Eternal Song).
Having scrutinised the Unknowable and the Unthinkable. He has realised the Bani (the Eternal Song).

Doolan Sahib speaketh:
Word is the lock and Word is the key thereto,
With the chains of the Word, all are bound.
The Lord resideth in the form of the Word,
I bow my head at Its Feet.

Charan Dass speaks:
Ever since I heard the limitless Divine Song (Anhad), reverberating throughout,
The Indrayas (organs) have become tired of going out,
And the mind has shed all its ramifications,
All desires have been satisfied.
Like a mad man, I have lost myself in the Word, and obtained complete oneness with It.

Swami Shibdayal Singh Ji describes the Word as:
The Sound or the Word is the prime cause of all. It is also the be-all and the end-all. The three regions and the fourth were made by It. The Word and the spirit are of the same origin and both spring from the essence of the Nameless One. It is both the cause and the effect, and all were created by It. The Word is the preceptor, as well as the disciple and is resounding in the heart of everyone. The Word is water and It is the fish, also. Kabir spoke only of this Word. Nanak and Tulsi proclaimed the same Truth. The king and the minister, both are Word personified. Radha Soami (the Lord of the Spirit) says: 'My brave son, listen to It.'

The Word (Sound) is echoing and re-echoing in the whole of creation. There is no place without It. It is resounding in living temple of the human body.

The Word forms a connecting link between man and God. Thus each body is the abode of the Almighty. This is Holy Naam – the Word permeating through all the pores of our bodies. With the help of it, we have to trace back our steps to the source from which we emanated. This is truly the only way back to God. There is no other way.

The Master says:
By taking to countless outward formularies and rituals, we cannot escape the inner fires of attachment and lust, etc. Millions of ways you may adopt and countless forms you may make, but not one is acceptable at His Court.

The Word withdraws us from the outer connections and recedes back in to It's Origins. It is the way that Guru Nanak taught, and so did the nine Sikh Gurus after him. Namdev, Ravidas, Kabir and others whose compositions have found place in the Guru Granth Sahib, were one and all the teachers of the Surat Shabd Yoga, or the Science of communion of the soul with the Word. There have been others, too, such as Dhruva, Prahlad, Tulsi, Shamas Tabrez, Mulana Rumi, Hafiz Shirazi, and Christ, whopracticed the Word. Dadu, Paltu, Soami Shib Dayal Singh, each taught the same Truth, in his own time.

The Holy Naam, or Word, can be practised by all alike, without the agency of tongue or palate. It does not require adherence to the outward observances of the social religions. This Word may be defined as the spirit-current which emanates from the One Being. It forms all the spiritual and material planes as It comes down, from plane to plane, reverberating in and out of all of them. As the lower planes are less subtle and more material than those above, the Word accordingly changes in sound as It comes down. Since It has to pass through five planes, It takes on five different sounds. These are five aspects of the one and the same Word. Guru Nanak deals with this at full length in stanza XV of the Jap Ji.

The whole of the Guru Granth Sahib is filled with beautiful pen-pictures, illustrative of the Word. There is no hymn which does not speak of It. A few quotations will suffice here. For exhaustive references, the reader is requested to refer to the voluminous treasure-house itself.

Through the writ of the Ever-flowing Pert of the Creator, we were attuned with the Lord, according to the instructions of the Master. We heard the five sounds, sounding in His Presence and thus rejoiced at our union with the Lord. – Mali M.5

Day and night, I am in communion with the Lord, with my mind fully convinced. The temple of my body has thus been beautified. The five Sounds of the limitless Music – the Word – are resounding. O, the Lord has entered my body. – Suhi M.1

The five Sounds become audible through the instructions of the Gurmukh – the Personified Word. Great is the luck of him who hears Them. The source of Joy and Peace (Word), I see as pervading everywhere. Through the Word, the Lord made His appearance and became manifest.
– Kanra M. 4

The five Sounds of the limitless Music (Word) are resounding within me. I am attracted to Them, as the Sarang or the sea-bird is attracted by the sight of water. Thy bondsman, Kabir, thus glorifies in Thee, O Lord, the Unknowable and above all human ken. – Parbhati Kabir

The Lord, revealing Himself in five Sounds of the Word, has come.

Guru Nanak speaketh:
He is the true Preceptor who shows the real Home within the temple of the body wherein five different Sound Currents are resounding and gives a clue of the Holy Naam. – Malar War M.1

Word is the Guru. Soul is the disciple of the Word – the melodious song. – Ramkali M. 1

All the handmaids that meet the five Sounds, become the Gurmukh (or the devoted disciples) and reach their True Home, within. Whoever by practice of the Word finds out his True Home, Nanak, shall serve him truly. – Malar War M.1

Bhai Gurdas, a Sikh sage, tells us in no ambiguous terms:
These five Sounds are heard when we rise above the body made of five elements.
When the sphere of five elements is transcended, you hear the five Sounds in all their sweet and powerful melody.

The other saints have likewise spoken on the same theme, as the following:

Everyday there are the flares of five drums
at His threshold, proclaiming His Greatness.
One who hears that drum-beat,
he is freed from egotism and envy
and passes beyond finite existence. – Shamas Tabrez

Silence thyself and listen thou to the melody of the five trumpets coming down from Heaven – the Heaven that is above all the skies Overhead. I laid the ears of my soul at the threshold of my heart and heard the shrouded mystery but did not see anyone opening his mouth. – Hafiz Sahib