One verse

Bhagavad Gita 17.5

17.5

अशास्त्रविहितं घोरं तप्यन्ते ये तपो जनाः | दम्भाहंकारसंयुक्ताः कामरागबलान्विताः ||१७-५||

aśāstravihitaṃ ghoraṃ tapyante ye tapo janāḥ . dambhāhaṃkārasaṃyuktāḥ kāmarāgabalānvitāḥ ||17-5||

aśāstra
not in the scriptures
vihitam
directed
ghoram
harmful to others
tapyante
undergo
ye
those who
tapaḥ
austerities
janāḥ
persons
dambha
with pride
ahaṅkāra
and egoism
saṁyuktāḥ
engaged
kāma
of lust
rāga
and attachment
bala
by the force
anvitāḥ
impelled

Those who undergo severe austerities and penances not recommended in the scriptures, performing them out of pride and egoism, who are impelled by lust and attachment, who are foolish and who torture the material elements of the body as well as the Supersoul dwelling within, are to be known as demons.