Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 6 · Calendar, Muhurta Elements
कालमानं मुहूर्ताङ्गानि च
तिथयः पक्षरंध्राख्या ह्यतिरूक्षा प्रकीर्तिताः ।समुद्रमनुरंध्रांकतत्त्वसंख्यास्तु नाडिकाः ॥ १३८ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 138.
... are called paksharandhra (the gaps of the fortnight). They are said to be very harsh. Their counts of ghatikas (24-minute units) are 4, 14, 9, 9 and 25.
Simple meaning: The 8th, 12th, 6th, 4th and 14th moon days are harsh. A set number of time units is given for each.
त्याज्याः स्युस्तासु तिथिषु क्रमात्पंच च सर्वदा ।
Leave those time units in those moon days. Odd moon days, except the new moon and 9th, are good.
तिथयस्तुप्रशस्तास्युर्मध्यमा प्रतिपत्सिता ।
Odd moon days are good and the bright 1st is middling. Avoid oil on the 6th, meat on the 8th.
पूर्णिमादर्शयोर्नारीसेवनं परिवर्जयेत् ।
Avoid being with a woman on full-moon and new-moon days. The rule continues in the next verse.