Verse 1.2.31-32

Sanskrit text, Unicode transliteration, Word-for-word and English translation of verse 1.2.31-32:

यस्यैकस्मिन् दिने शक्रा मादृशाः स्युश् चतुर्दश ।
मन्व्-आदि-युक्ता यस्याश् च चतुर्युग-सहस्रकम् ॥ ३१ ॥
निशा च तावतीत्थं याहो-रात्राणां शत-त्रयी ।
षष्ठ्य्-उत्तरा भवेद् वर्षं यस्यायुस् तच्-छतं श्रुतम् ॥ ३२ ॥

yasyaikasmin dine śakrā mādṛśāḥ syuś caturdaśa |
manv-ādi-yuktā yasyāś ca caturyuga-sahasrakam || 31 ||
niśā ca tāvatītthaṃ yāho-rātrāṇāṃ śata-trayī |
ṣaṣṭhy-uttarā bhaved varṣaṃ yasyāyus tac-chataṃ śrutam || 32 ||

In his one day, like me, fourteen Indras, fourteen Manus and all his sons that are born pass away. In this way one day measures a thousand catur-yugas, and similarly are his long nights. Three hundred and sixty such days and nights pass by like this, and his year ends. One hundred such years measure his lifespan.

Commentary: Dig-darśinī-ṭīkā with Bhāvānuvāda

(By Śrīla Sanātana Gosvāmī himself including a deep purport of that commentary)

In the word manvādi, the suffix ādi refers to the incarnations of Śrī Hari such as demigods, sages and all the sons of Manu.

This topic is explained in the Twelfth Canto (Śrīmad-Bhāgavatam or Bhāgavata Purāṇa 12.7.15):

मन्वन्तरं मनुर् देवा मनु-पुत्राः सुरेश्वराः
र्षयो’ंशावताराश् च हरेः षड्-विधम् उच्यते

manvantaraṃ manur devā manu-putrāḥ sureśvarāḥ
rṣayo’ṃśāvatārāś ca hareḥ ṣaḍ-vidham ucyate

“The interval of time in which these six kinds of avatāras of Hari’s jurisdiction manifest became renowned as a manvantara, that is, Manu, the multitude of demigods, sons of Manu, Indra, seven ṛṣīs and partial incarnations of Bhagavān Śrī Hari.”

Śrī Brahmā’s mere day is four thousand daiva-yugas (celestial millenniums) and the length of his night four thousand celestial millenniums. In this way after three hundred and sixty such days and nights, his year is complete. His duration of life spans one hundred such years. I have heard all these divine words from the mouth of the chief priest of the demigods, Śrī Bṛhaspati. Otherwise, I could not fully know all this. Since I, myself, have a brief lifespan, how could I know his lifespan?