Matsya Purana — The Ravi-Śayana
नैतद्विशीलाय न दाम्भिकाय कुतर्कदुष्टाय विनिन्दकाय प्रकाशनीयं व्रतमिन्दुमौलेर् यश्चापि निन्दामधिकां विधत्ते //
naitadviśīlāya na dāmbhikāya kutarkaduṣṭāya vinindakāya prakāśanīyaṃ vratamindumauler yaścāpi nindāmadhikāṃ vidhatte //
This vow of Indumauli (Śiva) is not to be disclosed to one of bad conduct, nor to a hypocrite, nor to one corrupted by perverse reasoning, nor to a fault-finder; nor should it be revealed to anyone who promotes excessive disparagement (of others or of the vow).
This verse does not address pralaya; it focuses on dharma—specifically, restricting the transmission of a Śiva-vrata to unfit recipients.
It teaches discernment and responsibility in religious instruction: a king or householder should uphold vows with integrity and avoid empowering hypocrites, slanderers, or sophists who would misuse sacred practices.
The ritual point is eligibility and confidentiality: the Śiva-vrata (vow) should be taught only to morally qualified practitioners, protecting the sanctity and proper performance of the observance.