Kural - 928

No more in secret drink, and then deny thy hidden fraud;
What in thy mind lies hid shall soon be known abroad

Explanation
Let (the drunkard) give up saying "I have never drunk"; (for) the moment (he drinks) he will simply betray his former attempt to conceal.

Tamil Transliteration
Kaliththariyen Enpadhu Kaivituka Nenjaththu
Oliththadhooum Aange Mikum.