Tithi-Nirṇaya for Vratas: Ekādaśī Rules, Saṅkrānti Punya-kāla, Eclipse Observances, and Prāyaścitta
तत्पुण्यं तिथिसंयुक्तं नक्षत्रं ग्राह्यमुच्यते । अर्द्धरात्रद्वये स्यातां नक्षत्रं च तिथिर्यदि ॥ १३ ॥
tatpuṇyaṃ tithisaṃyuktaṃ nakṣatraṃ grāhyamucyate | arddharātradvaye syātāṃ nakṣatraṃ ca tithiryadi || 13 ||
そのナクシャトラ(宿)は、相応のティティ(月日)と相合するとき、吉として採るべき宿であると言われる。もし宿とティティの双方が二度の真夜中にまたがる(両日に及ぶ)なら、その相合する期間をもって儀礼の時とせよ。
Narada (teaching within a Vedanga/kalā-style discussion of calendrical selection)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: none
It teaches that puṇya from rites depends on correct kāla-niṇaya (time-determination): the proper Nakṣatra must be taken only when it truly coincides with the intended Tithi, especially when the timing spans midnight.
Bhakti is strengthened when worship and vratas are performed at the scripturally valid time; this verse supports disciplined devotion by insisting on accurate tithi–nakṣatra conjunction rather than convenience.
Jyotiṣa (Vedāṅga astrology): a rule for selecting the ‘grāhya’ Nakṣatra based on its conjunction with Tithi, with special attention to cases where both extend across the two midnights.