Kural - 262

To 'penitents' sincere avails their 'penitence';
Where that is not, 'tis but a vain pretence

Explanation
Austerities can only be borne, and their benefits enjoyed, by those who have practised them (in a former birth); it will be useless for those who have not done so, to attempt to practise them (now).

Tamil Transliteration
Thavamum Thavamutaiyaarkku Aakum Adhanai
Aqdhilaar Merkol Vadhu.