Bhagavad Gita · 17.18

सत्कारमानपूजार्थं तपो दम्भेन चैव यत्।क्रियते तदिह प्रोक्तं राजसं चलमध्रुवम्॥

satkāra-māna-pūjārthaṁ tapo dambhena chaiva yat kriyate tad iha proktaṁ rājasaṁ chalam adhruvam

Austerity performed with hypocrisy, for the sake of gaining respect, honor, and reverence from others — that is said to be in the mode of passion. It is unstable and impermanent.

— Bhagavad Gita 17.18

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)