Shloka 25
Tithi-vicara
Determination of Tithi for Fasts, Parana, and Pitri Rites
क्षये वाप्यथवा वृद्धौ संप्राप्ते वा दिनोदये । उपोष्या द्वादशी पुण्या पूर्वविद्धां विवर्जयेत् ॥ २५ ॥
kṣaye vāpyathavā vṛddhau saṃprāpte vā dinodaye | upoṣyā dvādaśī puṇyā pūrvaviddhāṃ vivarjayet || 25 ||
无论该提提（tithi）是缩短（kṣaya）还是延长（vṛddhi），甚至在日出时开始，神圣的十二日（Dvādaśī）都应以斋戒奉行；应避开被前一提提“穿刺/侵入”的十二日（pūrvaviddhā）。
Narada (teaching tithi-based vrata procedure in the Uttara-Bhaga context)
Vrata: Dvādaśī (connected to Ekādaśī-vrata observance)
Primary Rasa: shanta
Secondary Rasa: bhakti
FAQs
It emphasizes that correct timing (tithi-śuddhi) is itself a form of dharma: Dvādaśī fasting is sacred, but it should be performed on a properly qualified Dvādaśī, avoiding impurity caused by overlap with the prior tithi (pūrvaviddhā).
By prescribing careful observance of Dvādaśī (closely linked with Vaiṣṇava vrata discipline), it frames bhakti as disciplined worship—devotion expressed through regulated fasting and adherence to scriptural calendrical rules.
Jyotiṣa (Vedāṅga astrology/calendar science): it uses technical tithi conditions like kṣaya (shortened tithi), vṛddhi (extended tithi), sunrise-based determination, and the rule to reject a pūrvaviddhā tithi for vrata decisions.