Source:
Hatim used to meet with disciples and people interested in discussing various subjects with him.
Once, a girl came to him to ask a question. However, while she asked, she ended up flatulating.
Noticing the girl's embarrassment, Hatim said, "Speak louder! I can't hear you properly!" So he made her think that he had not heard the sound of the flatus.
For fifteen years, while the woman lived, Hatim pretended to have difficulty listening to everyone who came to talk to him.
After the girl's death, however, he began to answer questions promptly. For this reason, he became known as Hatim al-Asamm (the Deaf).