Kural - 785

Not association constant, not affection's token bind;
'Tis the unison of feeling friends unites of kindred mind

Explanation
Living together and holding frequent intercourse are not necessary (for friendship); (mutual) understanding can alone create a claim for it.

Tamil Transliteration
Punarchchi Pazhakudhal Ventaa Unarchchidhaan
Natpaang Kizhamai Tharum.