Bhagavad Gita · 2.36

अवाच्यवादांश्च बहून्वदिष्यन्ति तवाहिताः।निन्दन्तस्तव सामर्थ्यं ततो दुःखतरं नु किम्॥

avāchya-vādāṁśh cha bahūn vadiṣhyanti tavāhitāḥ nindantas tava sāmarthyaṁ tato duḥkhataraṁ nu kim

Your enemies will speak many words of slander, deriding your ability. What could be more painful than that?

— Bhagavad Gita 2.36

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