Tithi-Nirṇaya for Vratas: Ekādaśī Rules, Saṅkrānti Punya-kāla, Eclipse Observances, and Prāyaścitta
अर्केऽह्नि पर्वरारौ च चतुर्दश्यष्टमी दिवा । एकादश्यामहोरात्रं भुक्त्वा चांद्रायणं चरेत् ॥ ५६ ॥
arke'hni parvarārau ca caturdaśyaṣṭamī divā | ekādaśyāmahorātraṃ bhuktvā cāṃdrāyaṇaṃ caret || 56 ||
ஞாயிற்றுக்கிழமை பகலில், பர்வ-இரவில், சதுர்தசி அல்லது அஷ்டமி பகலில், அல்லது ஏகாதசி நாள்-இரவு முழுதும் உண்டு விட்டால்—சாந்திராயணப் பிராயச்சித்தம் செய்ய வேண்டும்.
Nārada (teaching in a dharma/vrata context, traditionally within Nārada–Sanatkumāra dialogue)
Vrata: Cāndrāyaṇa
Primary Rasa: bhayanaka
Secondary Rasa: shanta
It emphasizes tithi-based discipline: violating sacred fasting times (especially Ekādaśī and parva junctions) is treated as a dharmic lapse, remedied through the purifying Cāndrāyaṇa observance.
By safeguarding Ekādaśī and other sacred lunar timings, the verse supports steadiness in vrata and self-restraint—foundational supports for Viṣṇu-bhakti practice even when it is framed here as corrective penance.
It relies on calendrical computation of tithi and parva (a Jyotiṣa/Vedāṅga application): identifying Ekādaśī, aṣṭamī, caturdaśī, and parva-nights to determine proper ritual conduct and expiation.