Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 8 · Marriage
विवाहः
अपि सौम्यग्रहैर्युक्तं गुणैः सर्वैः समन्वितम् ।षडष्टरिष्फगे चंद्रे लग्नदोषः स्वसंज्ञकः ॥ ४५२ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 452.
Take a lagna (rising sign) joined by good planets, with all good points. It still has its own fault when the Moon is in the 6th, 8th or 12th from it.
Simple meaning: The Moon in the 6th, 8th or 12th spoils a lagna even when it looks good.
तल्लग्नं वर्जयेद्यत्नाज्जीवशुक्रसमन्वितम् ।
Drop such a lagna even with Jupiter and Venus, and whatever the Moon's sign.
अपि सर्वगुणोपेतं दंपत्योर्निधनप्रदम् ।
It may put the couple's life at risk. The Moon joined by any planet is the Samgraha fault.
तस्मिन्संग्रहदोषे तु विवाहं नैव कारयेत् ।
Do not marry in the Samgraha fault. The Sun with the Moon may bring poverty.