Rudra Hridaya Upanishad

Om ! May He protect us both together; may He nourish us both together;
May we work conjointly with great energy,
May our study be vigorous and effective;
May we not mutually dispute (or may we not hate any).
Om ! Let there be Peace in me !
Let there be Peace in my environment !
Let there be Peace in the forces that act on me !

Now, at this moment, I take refuge in that Pure State of the Supreme Absolute which can be known by the Vidya, called the Rudra Hridaya Upanishad.
After prostrating before the celebrated form of Sri Mahadeva-Rudra in his heart, adoring the sacred Bhasma and Rudraksha and mentally reciting the great Mahavakya-Mantra, Tarasara, Sri Suka asked his father Sri Vyasa Maharshi, thus:
Who is the real God of gods? In whom are all these existences established? By worshipping whom, can I please the Devas in whole?

Hearing these words, Sri Veda Vyasa replied thus:
Rudra is the embodiment of all Devas. All devas are merely different manifestations of Sri Rudra Himself. On the right side of Rudra, there is the sun, then the four-headed Brahma, and then three Agnis (fires). On the left side, there exist Sri Umadevi, and also Vishnu and Soma (moon).
Uma Herself is the form of Vishnu. Vishnu Himself is the form of the moon. Therefore, those who worship Lord Vishnu, worship Siva Himself. And those who worship Siva, worship Lord Vishnu in reality. Those who envy and hate Sri Rudra, are actually hating Sri Vishnu. Those who decry Lord Siva, decry Vishnu Himself.

Rudra is the generator of the seed. Vishnu is the embryo of the seed. Siva Himself is Brahma and Brahma Himself is Agni. Rudra is full of Brahma and Vishnu. The whole world is full of Agni and Soma. The masculine gender is Lord Siva. The feminine gender is Sri Bhavani Devi. All the mobile and immobile creation of this universe, is filled up with Uma and Rudra. The Vyakta is Sri Uma, and the Avyakta is Lord Siva. The combination of Uma and Sankara is Vishnu.

Hence everybody should prostrate to Sri Maha Vishnu with great devotion. He is the Atman. He is the Paramatman. He is the Antaratman. Brahma is the Antaratman. Siva is the Paramatman. Vishnu is the Eternal Atman of all this universe. This whole creation of Svarga, Martya and Patala Lokas is a big tree. Vishnu is the top portion (branches) of this tree. Brahma is the stem. The root is Lord Siva.
The effect is Vishnu. The action is Brahma. The cause is Siva. For the benefit of the worlds. Rudra has taken these three forms.
Rudra is Dharma. Vishnu is the world. Brahma is Knowledge. Therefore, do Kirtan of His name, ‘Rudra’, ‘Rudra’. By singing like this, the hallowed name of this great Lord, all your sins will be destroyed.
Rudra is man. Uma is woman. Prostrations to Him and Her. Rudra is Brahma. Uma is Sarasvati. Prostrations to Him and Her. Rudra is Vishnu. Uma is Lakshmi. Prostrations to Him and Her. Rudra is Sun. Uma is shadow. Prostrations to Him and Her. Rudra is moon. Uma is star. Prostrations to Him and Her. Rudra is day. Uma is night. Prostrations to Him and Her. Rudra is Yajna. Uma is Vedi.
Prostrations to Him and Her. Rudra is Agni, Uma is Svaha. Prostrations to Him and Her. Rudra is Veda. Uma is Sastra. Prostrations to Him and Her. Rudra is tree. Uma is creeper. Prostrations to Him and Her. Rudra is scent. Uma is flower. Prostrations to Him and Her. Rudra is meaning. Uma is word. Prostrations to Him and Her. Rudra is Linga. Uma is Pitha. Prostrations to Him and Her.
The devotee should worship Sri Rudra and Uma with these Mantras referred to above. O my son, Suka! With these hymns, you should meditate on the Eternal Para-Brahman, which is beyond the reach of the senses, which is pure Existence, knowledge and Bliss and which cannot be understood either by the speech or by the mind. After knowing this, there is nothing more to be known, because everything is the form of That, and there is nothing separate from That.
There are two Vidyas to be known. They are Para and Apara. Apara Vidya is the embodiment of the four Vedas and their six Angas. They do not deal with the Nature of the Atman. But the Para Vidya is called the Moksha-Sastra. It deals with that supreme philosophy of the Absolute Truth, ununderstandable, impersonal, Nirguna, Nirakara, without ears, without eyes, without hands, without feet, eternal, omnipresent, imperishable, and knowable by the intelligent daring sages.
From that Lord Siva who performs a terrible penance in the form of Supreme Jnana-Marga, this whole world is created which is the food of the mortals. This world is Maya. It seems to appear just like a dream. It is superimposed on the Lord just like a rope on a serpent. This is the eternal Truth.
here is no creation in reality. All is absolute. All is Truth. Knowing this, one is liberated at once.
Only through Jnana, you can get rid of this Samsara. Only through Jnana, you can understand this existence and never through Karma. Understand this through the guidance of a Brahmanishtha-Srotriya Guru. The Guru will give the disciple all the necessary knowledge of Brahman, the Absolute. By cutting off the bondage of Ajnana or Avidya, one should take refuge in Lord Sadasiva. This is the real wisdom to be understood by an aspirant seeking after Truth.
The Pranava is the bow. The Atman is the arrow. The Para-Brahman is the target. Just like the arrow, the Atman will become one with Brahman.
But all these three, the bow, the arrow and the target are not different from that Sadasiva. There do not shine the bodies of the sun, moon or the stars. There does not blow the wind, there do not exist many Devatas. He, the One Lord only exists. He only, the Purity of purities, shines for ever and ever.
There are two birds in this body, the Jiva and the Paramatman. The Jiva eats the fruit of his Karmas, but the Paramatman is untouched by anything. The Paramatman is only the Sakshi. He does not do anything. He only assumes the form of the Jiva through His Maya, just as the Akasa inside a pot seems to be different from the Akasa outside and assumes the form of the pot. In reality all is Siva, Advaita, the One Absolute. There is no difference of whatever kind.
When all is understood to be One, Omkara, the Absolute, there is no sorrow, there is no Maya. Then the attainment of the Advaita-Paramananda is very easy. Think that you are the basis of all this universe, you are the One, Kevala, Sat-Chit-Ghana. All people cannot understand this Truth. Those devoid of Maya can know this secret. After knowing this, the Atman does not move towards any place at any time. It becomes one with the Absolute, just like Ghatakasa with Paramakasa. Just as Akasa does not move anywhere, similarly this Atman does not have any movement. It becomes one with OM.

One who knows this great secret Truth is the real Muni. He becomes the Para-Brahman Itself. He becomes Satchidananda. He attains permanent peace.

Om ! May He protect us both together; may He nourish us both together;
May we work conjointly with great energy,
May our study be vigorous and effective;
May we not mutually dispute (or may we not hate any).
Om ! Let there be Peace in me !
Let there be Peace in my environment !
Let there be Peace in the forces that act on me !

by http://www.celextel.org/108upanishads/rudrahridaya.html