Kural - 817

From foes ten million fold a greater good you gain,
Than friendship yields that's formed with laughers vain

Explanation
What comes from enemies is a hundred million times more profitable than what comes from the friendship of those who cause only laughter.

Tamil Transliteration
Nakaivakaiya Raakiya Natpin Pakaivaraal
Paththatuththa Koti Urum.