Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 8 · Marriage
विवाहः
न जन्ममासे जन्मर्क्षे न जन्मदिवसेऽपि च ।आद्यगर्भसुतस्याथ दुहितुर्वा करग्रहः ॥ ४२१ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 421.
Do not marry a first-born son or daughter in the birth month. Nor in the birth nakshatra (star), nor on the birth day.
Simple meaning: 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.
उत्पातग्रहणादूर्द्धं सप्ताहमखिलग्रहे ।
Avoid seven days after a total eclipse and three after a partial one.
ग्रस्तास्ते त्रिदिनं पूर्वं पश्चाद्ग्रस्तोदयेऽथवा ।
Avoid days around an eclipse: three days, or seven if it falls at midnight.