Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 6 · Calendar, Muhurta Elements
कालमानं मुहूर्ताङ्गानि च
रक्तवर्णौ रविश्चंद्रौ गौरो भौमस्तु लोहितः ।दूर्वावर्णो बुधो जीवः पीतश्वेतस्तु भार्गवः ॥ १६२ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 162.
The Sun is red. The Moon is white. Mars is blood red. Mercury is the colour of durva grass. Jupiter is yellow. Venus is white.
Simple meaning: 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.
बाणाग्निलोचनानिह्यवेदबाहुशिलीमुखाः ।
These numbers mark the bad parts of the day for Tuesday to Saturday.
कुलिकाश्चोपकुलिका वारवेलास्तथा क्रमात् ।
The numbers above give three kinds of bad time, each an hour and a half, from Sunday on.