There was a certain old man who made a vow not to drink any water during the Fast of Forty Days. And when he became thirsty, he would wash a potter’s vessel, and fill it with water, and hang it up in front of him. Then the brethren asked him why and wherefore he acted thus, and he said, “That I may labour the more, and receive a reward from God.” Now he said this that he might incite them to great labours.

Paradisus Patrum