One verse

Srimad Bhagavatam 9.14.46

9.14.46

तस्य निर्मन्थनाज्जातो जातवेदा विभावसु: । त्रय्या स विद्यया राज्ञा पुत्रत्वे कल्पितस्त्रिवृत् ॥ ४६ ॥

tasya nirmanthanaj jato jata-veda vibhavasuh trayya sa vidyaya rajna putratve kalpitas tri-vrt

tasya
of Pururava
nirmanthanat
because of interaction
jatah
was born
jata-vedah
meant for material enjoyment according to the Vedic principles
vibhavasuh
a fire
trayya
following the Vedic principles
sah
the fire
vidyaya
by such a process
rajna
by the King
putratve
a son’s being born
kalpitah
it so became
tri-vrt
the three letters a-u-m combined together as om.

From Pururava’s rubbing of the aranis came a fire. By such a fire one can achieve all success in material enjoyment and be purified in seminal birth, initiation and in the performance of sacrifice, which are invoked with the combined letters a-u-m. Thus the fire was considered the son of King Pururava.