Śivapurāṇa, Books 1 and 7 · Chapter 7.1.8

iti śrīśivamahāpurāṇe saptamyāṃ vāyavīyasaṃhitāyāṃ pūrvakhaṇḍe kālamahimavarṇanaṃ nāma saptamo 'dhyāyaḥ
Chapter 8
ṛṣaya ūcuḥ
kena mānena kālesminnāyussaṃkhyā prakalpyate
saṃkhyārūpasya kālasya kaḥ punaḥ paramo 'vadhiḥ

vāyuruvāca
āyuṣo 'tra nimeṣākhyamādyamānaṃ pracakṣate
saṃkhyārūpasya kālasya śāṃttvatītakalāvadhi

akṣipakṣmaparikṣepo nimeṣaḥ parikalpitaḥ
tādṛśānāṃ nimeṣāṇāṃ kāṣṭhā daśa ca pañca ca

kāṣṭhāṃstriṃśatkalā nāma kalāṃstriṃśanmuhūrtakaḥ
muhūrtānāmapi triṃśadahorātraṃ pracakṣate

triṃśatsaṃkhyairahorātrairmāsaḥ pakṣadvayātmakaḥ

jñeyaṃ pitryamahorātraṃ māsaḥ kṛṣṇasitātmakaḥ

māsaistairayanaṃ ṣaḍbhirvarṣaṃ dve cāyanaṃ matam
laukikenaiva mānena abdo yo mānuṣaḥ smṛtaḥ

etaddivyamahorātramiti śāstrasya niścayaḥ
dakṣiṇaṃ cāyanaṃ rātristathodagayanaṃ dinam

māsastriṃśadahorātrairdivyo mānuṣavatsmṛtaḥ
saṃvatsaro 'pi devānāṃ māsairdvādaśabhistathā

trīṇi varṣaśatānyeva ṣaṣṭivarṣayutānyapi
divyassaṃvatsaro jñeyo mānuṣeṇa prakīrtitaḥ

divyenaiva pramāṇena yugasaṃkhyā pravartate
catvāri bhārate varṣe yugāni kavayo viduḥ

pūrvaṃ kṛtayugaṃ nāma tatastretā vidhīyate
dvāparaṃ ca kaliścaiva yugānyetāni kṛtsnaśaḥ

catvāri tu sahasrāṇi varṣāṇāṃ tatkṛtaṃ yugam
tasya tāvacchatīsaṃdhyā saṃdhyāṃśaśca tathāvidhaḥ

itareṣu sasaṃdhyeṣu sasaṃdhyāṃśeṣu ca triṣu
ekāpāyena vartaṃte sahasrāṇi śatāni ca

etaddvādaśasāhasraṃ sādhikaṃ ca caturyugam
caturyugasahasraṃ yatsaṃkalpa iti kathyate

caturyugaikasaptatyā manoraṃtaramucyate
kalpe caturdaśaikasminmanūnāṃ parivṛttayaḥ

etena kramayogena kalpamanvaṃtarāṇi ca
saprajāni vyatītāni śataśo 'tha sahasraśaḥ

ajñeyatvācca sarveṣāmasaṃkhyeyatayā punaḥ
śakyo naivānupūrvyādvai teṣāṃ vaktuṃ suvistaraḥ

kalpo nāma divā prokto brahmaṇo 'vyaktajanmanaḥ
kalpānāṃ vai sahasraṃ ca brāhmaṃ varṣamihocyate

varṣāṇāmaṣṭasāhasraṃ yacca tadbrahmaṇo yugam
savanaṃ yugasāhasraṃ brahmaṇaḥ padmajanmanaḥ

savanānāṃ sahasraṃ ca triguṇaṃ trivṛtaṃ tathā
kalpyate sakalaḥ kālo brahmaṇaḥ parameṣṭhinaḥ

tasya vai divase yāṃti caturdaśa puraṃdarāḥ
śatāni māse catvāri viṃśatyā sahitāni ca

abde pañca sahasrāṇi catvāriṃśadyutāni ca
catvāriṃśatsahasrāṇi pañca lakṣāṇi cāyuṣi

brahmā viṣṇordine caiko viṣṇū rudradine tathā
īśvarasya dine rudrassadākhyasya tatheśvaraḥ

sākṣācchivasya tatsaṃkhyastathā so 'pi sadāśivaḥ
catvāriṃśatsahasrāṇi pañcalakṣāṇi cāyuṣi

tasminsākṣācchivenaiṣa kālātmā sampravartate // ŚivP_7.1,8.26*1ab/
yattatsṛṣṭessamākhyātaṃ kālāntaramiha dvijāḥ // ŚivP_7.1,8.26*1cd/
etatkālāntaraṃ jñeyamaharvai pārameśvaram // ŚivP_7.1,8.26*2ab/
rātriśca tāvatī jñeyā parameśasya kṛtsnaśaḥ // ŚivP_7.1,8.26*2cd/
ahastasya tu yā sṛṣṭī rātriśca pralayaḥ smṛtaḥ
aharna vidyate tasya na rātririti dhārayet

eṣopacāraḥ kriyate lokānāṃ hitakāmyayā
prajāḥ prajānāṃ patayo mūrtayaśca surāsurāḥ

indriyāṇīndriyārthāśca mahābhūtāni pañca ca
tanmātrāṇyatha bhūtādirbuddhiśca saha daivataḥ

ahastiṣṭhaṃti sarvāṇi pārameśasya dhīmataḥ
aharaṃte pralīyante rātryante viśvasaṃbhavaḥ

yo viśvātmā karmakālasvabhāvādyarthe śaktiryasya nollaṃghanīyā
yasyaivājñādhīnametatsamastaṃ namastasmai mahate śaṃkarāya