Kural - 840

Like him who seeks his couch with unwashed feet,
Is fool whose foot intrudes where wise men meet

Explanation
The appearance of a fool in an assembly of the learned is like placing (one's) unwashed feet on a bed.

Tamil Transliteration
Kazhaaakkaal Palliyul Vaiththatraal Saandror
Kuzhaaaththup Pedhai Pukal.