17:19
मूढग्राहेणात्मनो यत्पीडया क्रियते तपः ।
परस्योत्सादनार्थं वा तत्तामसमुदाहृतम् ॥१७- १९॥
mooDhagraaheNaatmano yatpiiDayaa kriyate tapaH ।
parasyotsaadanaarthaM waa tattaamasamudaahRRitam ॥१७- १९॥
Source: Automatic ITRANS Transliteration
Those austerities taken out of ignorance, self-flagellations,
Or for the purpose of harming others, are tamasic exemplars.
Source: Milind S. Pandit
Austerity performed without proper understanding, or with self-torture, or for harming others, is declared as Taamasika austerity.
And those penances and austerities which are performed foolishly by means of obstinate self-torture, or to destroy or injure others, are said to be in the mode of ignorance.
Source: Bhagavad Gita As It Is