Manava Dharmashastra 1.68

1.68

brahmā prajānāṃ sraṣṭā tasya yo lokastatra kṣapāhasyāhorātrasya yatpramāṇaṃ yugānāṃ caitatsamāsataḥ saṃkṣepeṇa nibodhata matsakāśācchṛṇuta | ekaikaśaḥ ekaikasya yugasya | vakṣyamāṇasya prakaraṇasya piṇḍārthakathanātho'yaṃ śloka śrotṝṇāmavadyānārthaḥ | tathā ca saṃbudhyante nibodhateti | prakṛte kālavibhāge punaḥ pratijñānaṃ prakaraṇāntaratvajñāpanārtham | tena vakṣyamāṇo'rtho na śāstrārambhaśeṣa eva, api tu dharmāyāpi | tathā ca vakṣyati 'brāhmaṃ puṇyamaharvi'duriti' tadvijñānācca puṇyaṃ bhavatī tyarthaḥ |

Learn in brief, in due order, the measure of the Brahmic ‘day and night,’ as also that of the ‘Time-cycles’ (Yugas) one by one.—(68)

Medhātithi’s commentary (manubhāṣya):
‘Brahmā,’—The creator of living beings, has a region of his own; and what is going to be described is of Day and Night as obtaining in that region;—‘as also of the Time-cycles.’—‘Learn’ all this, ‘in brief,’ summarily; i.e., hear it from me.—‘one by one’—that is, of each time-cycle separately.

The present verse serves as the summary of what is going to be described, intended to draw the attention of the audience; it is with this view that they are exhorted to ‘learn.’—The ‘division of time’ having been already mentioned as the subject-matter of the context, the reiterated promise (implied in the exhortation to ‘learn’) is meant to indicate that a fresh subject is going to be introduced; the idea being that what is going to be described now is not merely what remains of the afore-mentioned ‘division of time,’ but it is also conducive to merit; as will be directly stated in verse 73, where it is stated that ‘Brahma’s day is known to be sacred’; which means that the knowledge of it brings merit.—(68)