Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 2 · Signs, Planets, Birth
जातकम् १
लग्ने शेष्टमगेष्टेशे तनुस्थे पंचवत्सरम् ।कवीज्ययोगे सौम्याब्जौ लग्ने मृत्यौ च स्वेषवः ॥ ११८ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 55, verse 118.
The lagna (rising sign) lord in the 8th and the 8th lord in the lagna: life may be shortened to five years. Venus and Jupiter together, with Mercury and the Moon in the lagna and the 8th: 50 years.
Simple meaning: Lagna and 8th lords swapped may shorten life to five years. Another placement gives fifty.
एतद्योगजमायुः स्यादथ स्पष्टमुदीर्यते ।
The exact life is worked out with a method that follows the strongest of the Sun and Moon.
अंशायुः सबले लग्ने तत्साधनमथो शृणु ।
If the rising sign is strongest, the degree method is used. Full years for each planet are listed.
नखा विधुर्द्वावंकाश्च धृतिः स्वाक्षिखमार्गणाः ॥ १२१ ॥
The natural years for each planet are listed.