Tithi-Nirṇaya for Vratas: Ekādaśī Rules, Saṅkrānti Punya-kāla, Eclipse Observances, and Prāyaścitta
परविद्धाः प्रशस्ताः स्युर्न ग्राह्याः पूर्वसंयुताः । नागविद्धा तु या षष्टी शिवविद्धा तु सप्तमी ॥ ४ ॥
paraviddhāḥ praśastāḥ syurna grāhyāḥ pūrvasaṃyutāḥ | nāgaviddhā tu yā ṣaṣṭī śivaviddhā tu saptamī || 4 ||
Las tithis “penetradas” en el día siguiente (paraviddhā) se consideran loables; en cambio, las unidas al día anterior (pūrvasaṃyutā) no deben aceptarse. Debe evitarse una Ṣaṣṭhī perforada por Nāga, y también una Saptamī perforada por Śiva.
Narada (teaching tithi/vṛta-nirṇaya principles in the Narada Purana tradition)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: bhayanaka
It emphasizes dharmic precision in observances: choosing the correct tithi-lakṣaṇa (timing characteristics) safeguards the purity and fruit of a vrata, showing that devotion should be supported by proper ritual discernment.
Bhakti is not presented as careless sentiment; the verse implies that sincere worship is strengthened when aligned with śāstra-based timing (tithi-nirṇaya), avoiding doṣa-tainted days that can weaken the intended religious merit.
It highlights Vedāṅga Jyotiṣa/Pañcāṅga practice: determining whether a tithi is paraviddhā or pūrvasaṃyutā and recognizing specific ‘viddha’ doṣas (Nāga-viddhā, Śiva-viddhā) while fixing vrata dates.