Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 8 · Marriage
विवाहः
न चेद्वान्योन्यपतिना शुभमित्रेण वा तथा ।वरस्य मृत्युः स्यात्ताभ्यां सप्तसप्तोदयांशकौ ॥ ४४२ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 442.
If not, they may be looked at by each other's lords, or by a good friendly planet. Without this, the groom's life may be at risk. Then take the 7th sign and the 7th navamsha (one-ninth part of a sign) from those two.
Simple meaning: If no lord or friendly planet sees the lagna and navamsha, the groom's life may be at risk.
एवं तौ न युतौ दृष्टौ मुत्युर्वध्वाः करग्रहे ।
If the 7ths get no help, the bride's life may be at risk at marriage. Avoid the Sun's crossing.
विवाहादिषु कार्येषु नाड्यः षोडशषोडश ।
Avoid 16 ghatikas on each side of the Sun's sign change. Use good six divisions for marriage.
भृगुषष्ठाह्वयो दोषो लग्नात्षष्ठगते सिते ।
Never use a lagna with Venus in the 6th, even if Venus is strong.