Hṛṣīkeśendriyātmane. The mind is the director of the senses, and Lord Aniruddha is the director of the mind. In order to execute devotional service, one has to fix his mind on the lotus feet of Kṛṣṇa; therefore Lord Śiva prays to the controller of the mind, Lord Aniruddha, to be pleased to help him engage his mind on the lotus feet of the Lord. It is stated in Bhagavad-gītā (BG 9.34): man-manā bhava mad-bhakto mad-yājī mām. namaskuru. The mind has to be engaged in meditation on the lotus feet of the Lord in order to execute devotional service. It is also stated in Bhagavad-gītā (BG 15.15), mattaḥ smṛtir jñānam apohanaṁ ca: from the Lord come remembrance, knowledge and forgetfulness. Thus if Lord Aniruddha is pleased, He can help the mind engage in the service of the Lord. It is also indicated in this verse that Lord Aniruddha is the sun-god by virtue of His expansions. Since the predominating deity of the sun is an expansion of Lord Aniruddha, Lord Śiva also prays to the sun-god in this verse.
Lord Kṛṣṇa, by His quadruple expansion (Vāsudeva, Saṅkarṣaṇa, Pradyumna and Aniruddha), is the Lord of psychic action—namely thinking, feeling, willing and acting. Lord Śiva prays to Lord Aniruddha as the sun-god, who is the controlling deity of the external material elements which constitute the construction of the material body. According to Śrīla Viśvanātha Cakravartī Ṭhākura, the word paramahaṁsa is also another name for the sun-god. The sun-god is addressed herein as nibhṛtātmane, which indicates that he always maintains the various planets by manipulating the rainfall. The sun-god evaporates water from the seas and oceans and then forms the water into clouds and distributes it over land. When there is sufficient rainfall grains are produced, and these grains maintain living entities in each and every planet. The sun-god is also addressed herein as pūrṇa, or complete, because the rays emanating from the sun have no end. For millions and millions of years since the creation of this universe, the sun-god has been supplying heat and light without diminution. The word paramahaṁsa is applied to persons who are completely cleansed. When there is sufficient sunshine, the mind remains clear and transparent—in other words, the sun-god helps the mind of the living entity to become situated on the platform of paramahaṁsa. Thus Lord Śiva prays to Aniruddha to be kind upon him so that his mind will always be in the perfect state of cleanliness and will be engaged in the devotional service of the Lord. Just as fire sterilizes all unclean things, the sun-god also keeps everything sterilized, especially dirty things within the mind, thus enabling one to attain elevation to the platform of spiritual understanding.