Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 10
Sanskrit:
न सभां प्रविशेत् प्राज्ञ: सभ्यदोषाननुस्मरन् । अब्रुवन् विब्रुवन्नज्ञो नर: किल्बिषमश्नुते ॥ १० ॥
ITRANS:
na sabhāṁ praviśet prājñaḥsabhya-doṣān anusmaranabruvan vibruvann ajñonaraḥ kilbiṣam aśnute
Translation:
A wise person should not enter an assembly if he knows the participants there are committing acts of impropriety. And if, having entered such an assembly, he fails to speak the truth, speaks falsely or pleads ignorance, he will certainly incur sin.