One verse

Srimad Bhagavatam 10.54.40

10.54.40

क्षत्रियाणामयं धर्म: प्रजापतिविनिर्मित: । भ्रातापि भ्रातरं हन्याद् येन घोरतमस्तत: ॥ ४० ॥

kṣatriyāṇām ayaṁ dharmaḥ prajāpati-vinirmitaḥ bhrātāpi bhrātaraṁ hanyād yena ghoratamas tataḥ

kṣatriyāṇām
of warriors
ayam
this
dharmaḥ
code of sacred duty
prajāpati
by the original progenitor, Lord Brahmā
vinirmitaḥ
established
bhrātā
a brother
api
even
bhrātaram
his brother
hanyāt
has to kill
yena
by which (code)
ghora-tamaḥ
most terrible
tataḥ
therefore

[Turning to Rukmiṇī, Balarāma continued:] The code of sacred duty for warriors established by Lord Brahmā enjoins that one may have to kill even his own brother. That is indeed a most dreadful law.