Kural - 327

Though thine own life for that spared life the price must pay,
Take not from aught that lives gift of sweet life away

Explanation
Let no one do that which would destroy the life of another, although he should by so doing, lose his own life.

Tamil Transliteration
Thannuyir Neeppinum Seyyarka Thaanpiridhu
Innuyir Neekkum Vinai.