Source: Shaheed Murtada Mutahhari, The Narrative of Veracious, Vol.2, STORY NO.103, p.75-76
An old man was busy doing his Wudu’ statutory ablution, but he was not performing it in a correct manner. The children, Imam Hasan (‘a) and Imam Husayn (‘a) were watching the old man doing his Wudu’ statutory ablution. There was no reason to hesitate, for it is incumbent to teach the religious questions and guide the ignorant: It was necessary to make the old man familiar with the correct Wudu’ statutory ablution. Nevertheless, if he was directly said to correct his Wudu’, perhaps it would make him annoyed and he might have a bitter memory of Wudu’ for ever. In addition to that, who knows, perhaps he feels humiliated by this notification, becomes obstinate and never yields to the act of worship.
The two children, having meditated upon the way to call indirectly the old man’s attention to correct his mistake, began to debate in such a manner that the old man could hear them.

One said: “My Wudu’ is more perfect than yours.
The other one replied: “My Wudu’ is better than yours.
The boys came to an agreement to perform their ‘Wudu’ in the presence of the old man so that he would arbitrate between them.
As agreed, they performed their Wudu’ perfectly and correctly under his supervision. The old man realized how the correct Wudu’ must be performed. He came to know intuitively the intention of the two boys and was firmly affected by their genuine kindness, intelligence and sagacity.
He said: “The Wudu’ statutory ablution done by you both is correct and complete. I am the ignorant old. Who do not know to perform correct Wudu’. I am grateful that you made me admonished for the solicitude that you show to the community of your grandfather.”1

NOTES
1. Bihãr uI-Anwar, v. 10, p. 89.