Sanskrit
अशास्त्रविहितं घोरं तप्यन्ते ये तपो जनाः । दम्भाहङ्कारसंयुक्ताः कामरागबलान्विताः ॥
aśāstravihitaṃ ghoraṃ tapyante ye tapo janāḥ dambhāhaṅkārasaṃyuktāḥ kāmarāgabalānvitāḥ
Translation
The men who perform severe austerities, unenjoined by the Scriptures, wedded to vanity and egoism, impelled by the force of their desires and passions,
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
Before returning to the threefold structure, Krishna inserts a pointed aside about a specific failure mode: severe, scripturally unwarranted austerity (tapas) driven by vanity, ego, and craving rather than discipline. This sentence runs on into verse 6 for its verdict, but note the setup already answers Arjuna’s opening question obliquely — the problem was never “unscriptural” as such, it’s what’s actually motivating the practice underneath.