One verse

Srimad Bhagavatam 12.6.43

12.6.43

ततोऽक्षरसमाम्नायमसृजद् भगवानज: । अन्तस्थोष्मस्वरस्पर्शह्रस्वदीर्घादिलक्षणम् ॥ ४३ ॥

tato ’kṣara-samāmnāyam asṛjad bhagavān ajaḥ antasthoṣma-svara-sparśa- hrasva-dīrghādi-lakṣaṇam

tataḥ
from that oṁkāra
akṣara
of the different sounds
samāmnāyam
the total collection
asṛjat
created
bhagavān
the powerful demigod
ajaḥ
unborn Brahmā
anta-stha
as the semivowels
uṣma
sibilants
svara
vowels
sparśa
and consonant stops
hrasva-dīrgha
in short and long forms
ādi
and so on
lakṣaṇam
characterized

From that oṁkāra Lord Brahmā created all the sounds of the alphabet — the vowels, consonants, semivowels, sibilants and others — distinguished by such features as long and short measure.