Kural - 105

The kindly aid's extent is of its worth no measure true;
Its worth is as the worth of him to whom the act you do

Explanation
The benefit itself is not the measure of the benefit; the worth of those who have received it is its measure.

Tamil Transliteration
Udhavi Varaiththandru Udhavi Udhavi
Seyappattaar Saalpin Varaiththu.