Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 6 · Calendar, Muhurta Elements
कालमानं मुहूर्ताङ्गानि च
बलप्रदस्य खेटस्य कर्म सिद्धचति यत्कृतम् ।तत्कर्म बलहीनस्य दुःखेनापि न सिद्धचति ॥ १६० ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 160.
Work belonging to a strong planet succeeds when it is done. The same work, for a weak planet, does not succeed even with hard effort.
Simple meaning: Work tied to a strong planet succeeds. Under a weak planet it fails, even with effort.
इंदुज्ञजीवशुक्राणां वासराः सर्वकर्मसु ।
The Moon, Mercury, Jupiter and Venus days suit all work. The other days suit only harsh work.
रक्तवर्णौ रविश्चंद्रौ गौरो भौमस्तु लोहितः ।
Each planet has a colour: Sun red, Moon white, Mars blood red, Mercury green, Jupiter yellow, Venus white.
कृष्णः सौरिः स्ववारेषु स्वस्ववर्णक्रिया हिताः ।
Saturn is black. Work in a planet's colour suits its own day. Bad-time numbers for Sunday and Monday follow.