Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 8 · Marriage
विवाहः
पश्चात्प्रागुदितः शुक्रो दशत्रिदिवसं शिशुः ।वृद्धः पंचदिनं पक्षं गुरुः पक्षं च सर्वतः ॥ ४१९ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 419.
Venus that rises in the west is a child for ten days. Rising in the east, it is a child for three days. Before setting, Venus is old for five days in the west and a fortnight in the east. Jupiter is a child for a fortnight and old for a fortnight, in both directions.
Simple meaning: Venus is weak 10 or 3 days after rising and 5 or 15 before setting. Jupiter, 15 days each.
अप्रबुद्धो हृषीकेशो यावत्तावन्न मंगलम् ।
No marriage while Vishnu sleeps, and none on the day of his festival.
न जन्ममासे जन्मर्क्षे न जन्मदिवसेऽपि च ।
A first child should not marry in the birth month, birth star or on the birthday.
नैवोद्वाहो ज्येष्ठपुत्रीपुत्रयोश्च परस्परम् ।
Two eldest children should not marry in Jyeshtha. If only one is eldest, Jyeshtha is fine.