Hazrat Hasan al-Basri once fell sick. His neighbour, an unbeliever, came to pay him a visit.

"O Imam," he exclaimed, "I detect a bad smell." The Imam told him it was caused by illness, but the neighbour insisted: "That is not the odor of sickness. It is a lavatory smell. For the love of Allah, tell me what it is!"
He had not noticed that sewage was leaking from his house into that of the Imam.

When the neighbour pressed him, the Imam finally said: "For some months your drain has been seeping through to our side. I tried to fix it, but without success."
His neighbour asked why he had not told him before, but the venerable Imam said: "I might have offended you."

The unbeliever was so impressed by this ethical refinement that he was ennobled with True Faith, for he recognized the Imam's morality as a ray of Islam.