In the banking industry, there are two types of investors. One invests part of his capital, reaps gains, and prides himself on his great success. Another person also invests part of his capital but realizes that his gains are small compared to what he could have earned had he invested more of his capital. He regrets his lack of vision, contemplates the gains he failed to achieve, and longs for better times.

So too is it among those who give charity (tzedakah). There are those who give a limited amount and bask in the self-satisfaction of giving. Then there are those who delve into the study of deep secrets of Torah and enjoy a meaningful, inspiring gathering with their fellow Jews. These givers regard their gifts to charity as paltry compared to what they could have accomplished with greater strength and commitment to the giving of tzedakah.

Igros Kodesh of the Previous Rebbe, Vol. 4, p. 45