उमामहेश्वरव्रतं—पञ्चाक्षरमन्त्रस्य माहात्म्यं, न्यासः, जपविधिः, सदाचारः, विनियोगः
जपादेव न संदेहो व्रतानां वै विशेषतः समाप्तिर्नान्यथा तस्माज् जपेत्पञ्चाक्षरीं शुभाम्
japādeva na saṃdeho vratānāṃ vai viśeṣataḥ samāptirnānyathā tasmāj japetpañcākṣarīṃ śubhām
By japa alone, there is no doubt—especially with regard to vratas—their true fulfillment is not attained by any other means. Therefore one should repeat the auspicious Pañcākṣarī, the five-syllabled mantra of Śiva.
Suta Goswami (narrating the Linga Purana teaching to the sages of Naimisharanya)
It teaches that external observances become spiritually complete through Śiva-mantra japa—especially the Pañcākṣarī—making mantra the inner core of Linga-pūjā and vrata.
Śiva as Pati is approached through the vibration of His mantra; japa becomes a direct means for the pashu (soul) to turn inward and move toward Śiva-tattva, beyond mere outer ritual.
Mantra-japa of the Pañcākṣarī (Namaḥ Śivāya), aligned with Pāśupata-oriented discipline where repeated remembrance purifies the mind and weakens pāśa (bondage).