Narada Purana — Purva Bhaga, Shloka 24
Mārkaṇḍeya-varṇanam
The Description of Mārkaṇḍeya
ऋतुर्मासद्वयेन स्यात्तत्त्रयेणायनं स्मृतम् । तद्द्वयेन भवेदब्दः स देवानां दिनं भवेत् ॥ २४ ॥
ṛturmāsadvayena syāttattrayeṇāyanaṃ smṛtam | taddvayena bhavedabdaḥ sa devānāṃ dinaṃ bhavet || 24 ||
二か月で一つの季節（ṛtu）となり、その季節が三つ集まるとアヤナ（ayana、半年）と呼ばれる。二つのアヤナで一年（abda）となり、その一年は諸天（デーヴァ）にとって一日の長さである。
Sanatkumara (in dialogue with Narada)
Vrata: none
Primary Rasa: shanta
Secondary Rasa: adbhuta
FAQs
It places human time within a larger cosmic framework, reminding the practitioner that ritual life and dharma operate within divinely ordered cycles governed by kāla (Time).
While not directly teaching bhakti practices, it supports devotion by emphasizing proper sacred timing—devotional vows and worship become more aligned when performed according to divinely structured calendrical cycles.
Vedāṅga Jyotiṣa (astronomical/astrological timekeeping): it defines months, seasons (ṛtu), half-years (ayana), and the year (abda), and relates them to the Devas’ day for calendrical and ritual computation.