Kural - 509

Trust no man whom you have not fully tried,
When tested, in his prudence proved confide

Explanation
Let (a king) choose no one without previous consideration; after he has made his choice, let him unhesitatingly select for each such duties as are appropriate.

Tamil Transliteration
Therarka Yaaraiyum Theraadhu Therndhapin
Theruka Therum Porul.