Kural - 148

Manly excellence, that looks not on another's wife,
Is not virtue merely, 'tis full 'propriety' of life

Explanation
That noble manliness which looks not at the wife of another is the virtue and dignity of the great.

Tamil Transliteration
Piranmanai Nokkaadha Peraanmai Saandrorkku
Aranondro Aandra Vozhukku.