मनुस्मृति - मेधावी जडवल्लोक आचरेत्

नापृष्टः कस्यचिद्ब्रूयात् न चान्यायेन पृच्छतः ।
जानन्नपि हि मेधावी जडवल्लोक आचरेत् ॥

- मनुस्मृति

na apRuShTaH kasyachid brUyAt na cha anyAyena pRucChataH ।
jAnannapi hi medhAvI jaDavat loka Acharet ॥

- manu smRuti

One must never answer without being asked a question. One must never answer when the question is not posed with correct intentions (illegal, arrogance, etc..). Even after knowing everything, a wise man must act stupid in this world.

- Manu Smriti