Narada Purana (Jyotisha Selections) · by Vyasa
Chapter 6 · Calendar, Muhurta Elements
कालमानं मुहूर्ताङ्गानि च
संवतयोगो विज्ञेयः शुभकर्मविनाशकृत् ।आनन्दः कालदंडाख्यो धूम्रधातृसुधाकराः ॥ २३७ ॥
In the full Narada Purana (Purva Bhaga) this is chapter 56, verse 237.
...that is Samvata yoga (good or bad day mix). It can spoil good acts. Then Ananda, Kaladanda, Dhumra, Dhatri and Sudhakara.
Simple meaning: Those two pairs make Samvata, which can spoil good acts. The list of 28 day mixes begins with Ananda.
ध्वांक्षध्वजाख्यश्रीवत्सवज्रमुद्गरछत्रकाः ।
The list of day mixes goes on with twelve more names.
काणसिद्धिशुभा मृत्युमुशलांतककुंजराः ।
The list of twenty-eight day mixes ends with these eleven names.
योगाः स्वसंज्ञाफलदा अष्टाविंशतिरीरिताः ।
The 28 day mixes give results like their names. Sunday starts at Ashvini, Monday at Mrigashira.