Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 8 · Marriage
विवाहः
विवाहे बलमावश्यं दंपत्योर्गुरुसूर्ययोः ।चेत्पूजा यत्नतः कार्या दुर्बलग्रहयोस्तयोः ॥ ४२७ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 427.
In marriage, strength of Jupiter and the Sun is needed for the couple. If the two planets are weak, worship should be done with care.
Simple meaning: Jupiter and the Sun must be strong for the couple, or worship is done.
गोचरं वेधजं चाष्टवर्गजं रूपजं बलम् ।
Transit strength is the roughest. Blocking, ashtakavarga and counted strength are each finer.
चंद्रताराबलं वीक्ष्य ततः पंचांगजं बलम् ।
Check the Moon and star strength, then the almanac parts, which count one, two and three.
योगश्चतुर्गुणः पञ्चगुणं तिथ्यर्द्धसंज्ञितम् ।
Each part counts more in turn: yoga four, karana five, then the hour and the lagna.