Narada Purana — Purva Bhaga, Shloka 6
Tithi-Nirṇaya for Vratas: Ekādaśī Rules, Saṅkrānti Punya-kāla, Eclipse Observances, and Prāyaścitta
पूर्वविद्धं प्रकुर्वाणो नरकायोपद्यते । कृष्णपक्षे पूर्वविद्धां सत्पमीं च चतुर्दशीम् ॥ ६ ॥
pūrvaviddhaṃ prakurvāṇo narakāyopadyate | kṛṣṇapakṣe pūrvaviddhāṃ satpamīṃ ca caturdaśīm || 6 ||
若于“前触”之月日（pūrvaviddhā：在日之初段已现）而行仪轨者，必堕地狱。然于黑半月（kṛṣṇa-pakṣa）之中，七日（Saptamī）与十四日（Caturdaśī）当依前触（pūrvaviddhā）而守。
Narada (teaching nirṇaya rules within vrata/kalā discipline)
Vrata: none
Primary Rasa: bhayanaka
Secondary Rasa: shanta
FAQs
It stresses that correct timing (tithi-nirṇaya) is part of Dharma; performing a vow on the wrong tithi is treated as a serious ritual fault with harmful karmic consequences.
Bhakti in the Purāṇic tradition is expressed through disciplined observances; the verse teaches that devotion should be aligned with śāstric timing rather than personal convenience.
It highlights Jyotiṣa/Vedāṅga-based pañcāṅga application—deciding whether a tithi is to be taken as pūrvaviddhā (earlier contact) for specific lunar days in the kṛṣṇa-pakṣa.