Thirukkural- On Virtue- Hypocrisy-Kural-273

One who is incapable of mastering himself, trying to put on an air of strength,
Is like a cow grazing on forbidden pasture, under cover of a tiger"s skin.

A man without self-control misbehaving under an ascetic"s garb is like a cow grazing on forbidden area under cover of a tiger-skin. The fact that the imposter will be instantly spotted, is implied in the comparison, as a tiger will never eat grass. But at the same time the possibility of some harm being done, cannot be ruled out as ascetics are expected to have conquered the flesh and so would be normally taken on trust. This gives them an opportunity to misbehave, without being located in true colours, for some time. Lord Indira used the same subterfuge and reportedly suffered grievously for it. Of such imposters did Christ warn the faithful in the following words:

'Beware of false prophets, who come to you in sheep"s clothing, but inwardly they ware ravening wolves".