A person was advised by a holy man to gift a vegetable a day and told that he would attain great merit by doing so.
The poor man strictly followed the advice. After death, he was reborn in a royal family and grew up to become a king. He was able to recall what he had done in his past birth. So, he continued to gift a vegetable a day.
Surprisingly, after death, he was reborn as a beggar. The man was unable to comprehend the reason and so sought the advice of the holy man who had earlier blessed him.
From the sage, he learnt that prior to becoming a king he had been very poor and so a gift of a vegetable aday was sufficient to give him a lot of virtue.
On the other hand, as a king he was endowed with affluence. So, thereafter, the gift of just a vegetable a day was quite insufficient to earn him merit of any consequence.
The person realized that the extent of charity needed to earn a certain degree of merit depends upon one's financial status.