Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 8 · Marriage
विवाहः
नैवं कदाचिदुद्वाहो नैकदा मुंडनद्वयम् ।दिवाजातस्तु पितरं रात्रौ तु जननीं तथा ॥ ५१८ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 518.
Such a wedding must never be held, and two head-shavings must not be done at one time. One born by day may put the father's life at risk, and one born at night the mother's,
Simple meaning: Some weddings and rites must not be done twice together. Birth at certain times may risk a parent's life.
आत्मानं संध्ययोर्हंति नास्ति गंडे विपर्ययः ।
A twilight birth may risk the child's own life. A Moola birth may risk the father-in-law's life.
तदंत्यपादजो नैव तथाश्लेषाद्यपादजः ।
A boy born in Jyeshtha's last quarter may put an elder sibling at risk. Mula's last quarter does not.
आरभ्योद्वाहदिवसात् षष्ठे वाप्यष्टमे दिने ।
The bride enters the new home on the 6th, 8th, 10th or 7th day after the wedding.