One verse

Srimad Bhagavatam 2.10.46

2.10.46

अयं तु ब्रह्मण: कल्प: सविकल्प उदाहृत: । विधि: साधारणो यत्र सर्गा: प्राकृतवैकृता: ॥ ४६ ॥

ayam tu brahmanah kalpah savikalpa udahrtah vidhih sadharano yatra sargah prakrta-vaikrtah

ayam
this process of creation and annihilation
tu
but
brahmanah
of Brahma
kalpah
his one day
sa-vikalpah
along with the duration of the universes
udahrtah
exemplified
vidhih
regulative principles
sadharanah
in summary
yatra
wherein
sargah
creation
prakrta
in the matter of material nature
vaikrtah
disbursement.

This process of creation and annihilation described in summary herein is the regulative principle during the duration of Brahma’s one day. It is also the regulative principle in the creation of mahat, in which the material nature is dispersed.