Tirukkural-On Virtue-Not Coveting Another's Wife-Kural 147

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A virtuous householder is one who does not desire to violate the femininity of another man's wife.

Virtue in a householder has been specifically defined here, as the right conduct of a man who does not lust after his neighbour's wife.

The expression 'Penmai' is probably an echo from 'Tolkappiam' which says,
Penmaiyaavadhu katpulanaakiya thoar
Amaidhith thanmai adhu piraniyalaal
Penmai nayavaadhavan yenpadhanaalum unarka

(Thol-Sol : 57)

Femininity here, describes a larger concept of chastity, covering the control of all the senses and the virtuous householder is expected not to interfere with the least of its facets.