Adhyaya 89: शौचाचारलक्षणम् — सदाचार, भैक्ष्यचर्या, प्रायश्चित्त, द्रव्यशुद्धि, आशौच-निर्णय
ईक्षयेद्भास्करं देवं ब्रह्मकूर्चं ततः पिबेत् केवलं पञ्चगव्यं वा क्षीरं वा चात्मशुद्धये
īkṣayedbhāskaraṃ devaṃ brahmakūrcaṃ tataḥ pibet kevalaṃ pañcagavyaṃ vā kṣīraṃ vā cātmaśuddhaye
దైవభాస్కరుని దర్శించాలి; తరువాత బ్రహ్మకూర్చాన్ని పానము చేయాలి. లేదా ఆత్మశుద్ధి కోసం కేవలం పంచగవ్యమో, పాలనో సేవించాలి।
Suta Goswami (narrating Śaiva purification rites to the sages of Naimiṣāraṇya)
It prescribes ātma-śuddhi (inner purification) as a prerequisite for Śiva-liṅga worship—using auspicious darśana of Sūrya and purifying intake (brahma-kūrca/pañcagavya/milk) so the practitioner becomes ritually and mentally fit for Śaiva upāsanā.
Indirectly: it implies that approaching Pati (Śiva) requires the paśu to lessen mala and bondage through purification; Śiva-tattva is the supremely pure reality, and the seeker aligns with that purity through preparatory disciplines.
A preparatory śauca-prayoga: Sūrya-darśana followed by drinking a purificatory substance (brahma-kūrca, or pañcagavya, or milk) as an expiatory and sattva-enhancing rite before Śaiva observances.