Kural - 38

If no day passing idly, good to do each day you toil,
A stone it will be to block the way of future days of moil

Explanation
If one allows no day to pass without some good being done, his conduct will be a stone to block up the passage to other births.

Tamil Transliteration
Veezhnaal Pataaamai Nandraatrin Aqdhoruvan
Vaazhnaal Vazhiyataikkum Kal.