Thirukkural

வகையறச் சூழா தெழுதல் பகைவரைப் பாத்திப் படுப்பதோ ராறு.

Vakaiyarach Choozhaa Thezhudhal Pakaivaraip Paaththip Patuppadho Raaru

One way to promote the prosperity of an enemy, is (for a king) to set out (to war) without having thoroughly weighed his ability (to cope with its chances)