One verse

Srimad Bhagavatam 6.12.33

6.12.33

वज्रस्तु तत्कन्धरमाशुवेग: कृन्तन् समन्तात् परिवर्तमान: । न्यपातयत् तावदहर्गणेन यो ज्योतिषामयने वार्त्रहत्ये ॥ ३३ ॥

vajras tu tat-kandharam asu-vegah krntan samantat parivartamanah nyapatayat tavad ahar-ganena yo jyotisam ayane vartra-hatye

vajrah
the thunderbolt
tu
but
tat-kandharam
his neck
asu-vegah
although very fast
krntan
cutting
samantat
all around
parivartamanah
revolving
nyapatayat
caused to fall
tavat
so many
ahah-ganena
by days
yah
which
jyotisam
of the luminaries like the sun and moon
ayane
in moving to both sides of the equator
vartra-hatye
at the time suitable for killing Vrtrasura.

Although the thunderbolt revolved around Vrtrasura’s neck with great speed, separating his head from his body took one complete year—360 days, the time in which the sun, moon and other luminaries complete a northern and southern journey. Then, at the suitable time for Vrtrasura to be killed, his head fell to the ground.