Bhagavad Gita Chapter 17 Verse 5

Gita 17.5

अशास्त्रविहितम्, घोरम्, तप्यन्ते, ये, तपः, जनाः,
दम्भाहंकारसंयुक्ताः, कामरागबलान्विताः।।5।।

Gita 17.5

Ashaastrvihitam’, ghoram’, tapyante, ye, tapH, janaaH,
DambhaahankaarsanyuktaH, kaamraagbalaanvitaH ||5||

Translation: (Ye) who (janaaH) men (ashaastrvihitam’) not enjoined by the scriptures, only arbitrary (ghoram’) severe (tapH) austerity (tapyante) practice and (dambhaahankaarsanyuktaH) filled with hypocrisy and arrogance and (kaamraagbalaanvitaH) are also filled with attachment to desire and pride of the power of bhakti. (5)

Translation: Those men who only practice arbitrary severe austerity which is not enjoined by the scriptures and are equipped with hypocrisy and arrogance and with attachment to desire and pride of the power of bhakti.