Vedic texts speak of Reality, the underlying and immanent Principle as with out Name and Form.
This aspect of Reality is called Nirguna Brahman, Devoid of Attributes.
However as Reality is something to be realised, the Vedic people understood the difficulty of realising an Attribute- less Reality.

A Reality that can not be realised is a mere academic exercise.
As Hinduism addresses the issue of Life and Death in a practical way, it does not stop with mere abstractions, though it may appear so.
If Reality has to be known it can be through two sources.
One is by Knowing  ( mind) and another is by
Experiencing.
Knowing belongs to mind while experiencing is of the realm of the Heart (heart)
Realising Brahman through Experience is through the Bhakti Yoga, Path of Devotion.
This calls for total surrender to God.
But human mind being what it is , is never satisfied with following something without knowing it to be true.
This, knowing well that knowledge is relative and not entirely dependable.
So human mind seeks confirmation by the Mind.
Mind, to understand some concepts needs some thing to concentrate upon for mind can not concentrate and operate in a vacuum.
So two aspects of Reality  are explained in the Vedas.
One, the Nirguna Brahman without Attributes and another Saguna Brahman with Attributes.
This Saguna Aaradhana or worship ls worship of Gods be personifying them with Human Attributes in Perfection.
Therefore Nirguna and Saguna Brahman worship are recimmended to suit individual dispoilsitions.
One would find, in Hindu prayers, complete exposition of attributes to one God in Saguna Form of Worship.
In some prayers the Nirguna Brahman is worshiped that is ‘without Attributes’
But there are some Mahamantras which contain both Saguna and Nirguna worship.
For example, the Lalitha Sahasranama has both Saguna and Nirguna worship.
In the Vedic texts one finds this format in Sri Rudram addressed to Rudra, an aspect of Siva.
Contrary to what many think the SriRudram also addresses the Nirguna Brahman.
This is the reason why it is called as a Mahamantra.
In Sri Rudram the Universal Reality is invoked.
In later parts the Saguna asoect is worshiped.
As Sri Rudram contains both forms of worship, it is chanted while performing Abhisheka, bathing the Deity,irrespective of the Deity.
It may be Ganesa  , Subrahmanya  or  Devi.
Strictly speaking Vishnu Abhishaka is to be done with Sri Rudra aling with Purusha suktha, Narayana, Vishnu, Sri and Durga Suktha.
Some Vishnu temples avoid SriRudram.
All Abhisheka must be performed with the Five Sukthas and Sri Rudram.
Here below is an excerpt from Sri Rudran that addresses the Universal Reality.
‘ Original text (TS iv.5.5) 5th Anuvaka

namo bhavāya cha rudrāya cha
namaḥ śarvāya cha paśupataye cha
namo nīlagrīvāya cha śitikaṇṭhāya cha
namaḥ kapardine cha vyuptakeshāya cha
namaḥ sahasrākṣāya cha śatadhanvane cha
namo girīśāya cha śipiviṣṭāya cha

English Translation:

Prostration to the one who is the most dear (pleasant), to the one who is the most dreaded terroriser (frightening).
Prostration to the one who kills living beings with arrows, to the Lord (benefactor) of all living beings.
Prostration to the blue-necked one (disfigured (discoloured) naturally), to the one with whitened throat (throat smeared with Bhasma (ash); disfigured (discoloured) artificially).
Prostration to the wearer of matted tangled locks of hair, to him of shaven beard.
Prostration to him of a thousand eyes (view from one point to everywhere), to him who has the capability of hundred bowmen (view from everywhere to one point – concentration of the view from all directions.

* I began this article with the intention of writing on the benefits of Rudram and why Rudram is a Maha Mantra, on the request of a Reader but ended up with this article.
Shall write on Benefits of Rudram shortly.

Filed under: Hinduism Tagged: Brahman, chamakam, Hindu Prayers, namakam, Nirguna Brahman, Rudram, Saguna Brahman, siva prayers, Sri Rudram