Dimad bin Tha'laba (r.a.)
There was sensational news all around Makkah. People were mentioning something in the street, at home and in the market. Everybody was talking about the cause brought by Muhammad (pbuh). Some people were astonished by what they heard and accepted his cause while others increased their grudge and obstinacy against him. Those who found the right way gathered around him. The circle was expanding day by day. The ferocious polytheists were worried about it and they understood that they could not watch the fall of polytheism.
How could they prevent this person, who alienated them from the idols of their ancestors and who introduced a new religion? It was no laughing matter. Those who thought "This thing will not go on; it will end somehow" were mistaken because the most unexpected people sided with him.
One day, the notables of Makkah came together in a street and started to chat. They were talking about how to stop the light of Muhammad (pbuh) and how to stop this movement.
Abu Jahl was one of the leading people who were determined to extinguish the sun of guidance. This ferocious polytheist always supported and led all kinds of hostile plans. There were also two famous enemies of Islam like Utba bin Rabia and Umayya bin Khalaf with him. Abu Jahl started to talk. Abu Jahl, the father of ignorance, said:
"This man broke our unity. He eliminated our hopes. He accused our dead people of heresy. He condemned and insulted our gods."
These words, which provoked those around him, were also a manifestation of the disturbance felt in the face of the divine cause.
Umayya, who was angry, took the floor:
"This guy is really mad."
In fact, this statement was a declaration of weakness mixed with hatred.
Dimad, the famous warlock, heard this conversation as he passed by. When he heard Umayya say, "he is mad", he felt pity for Muhammad (pbuh) rather than hostility. He thought he was really mad and he thought his duty was to heal people like that. Besides, Muhammad (pbuh) was an old friend of his; He regarded it a duty of loyalty to save him from this trouble.
Dimad decided to find Muhammad (pbuh), to learn his problem and to heal him. For, he was the only psychiatrist in Makkah and the regions around it. He started to look for Muhammad (pbuh) until the evening but could not find him.
The next day, he looked for him again. Finally, he found him praying in the Kaaba. He was sitting for at-tahiyyat at Maqam Ibrahim. When he finished his prayer, Dimad approached him. He walked toward him cautiously because it could not be estimated what a mentally ill person would do. He said,
"O Abdulmuttalib's grandson! Turn toward me!"
The Messenger of Allah (pbuh) turned and said, "What do you want?"
He said, "I treat mental illnesses. If you want, I will to find a solution to your problem. Do not let your disease deteriorate. I healed those who were more seriously ill. Your tribe is talking about some bad traits in you. They say that they have abandoned hope about you, that you have broken their unity, that you have accused their dead people of heresy and that you have condemned their gods. Only a person who has gone mad does so."
The Messenger of Allah listened to Dimad patiently and silently. For, he would always listen to the speaker first and then would say or do what was necessary in the best way. He addressed Dimad, who was still in the in the swamp of ignorance and had the belief of idols in his mind.
The Messenger of Allah started his words as follows: "Praise be to Allah. I praise only Him and I ask help from Him. Nobody can mislead a person whom Allah guides. If He misleads somebody, nobody can guide him. I witness that there is no god other than Allah, who has no partners." Then, he answered the charges made against him.
Dimad was surprised. For, the words he listened to were not the work of insanity; they were so concise and beautiful that even the most intelligent man in the world could not utter them. He was shocked. How did the notables of Quraysh dare to accuse him of "madness"? Or, was Dimad himself mad since Muhammad’s word sound perfect? He could not help saying,
"Please repeat what you said once again!"
The Prophet, whose duty was to tell people about his cause, did not mind repeating them. He repeated the same truths to Dimad once more in the same concise style. Dimad could not put up with it any longer and he began to speak loudly as follows:
"I have heard the words of the soothsayers, sorcerers and poets. I swear that I have never heard something like your words. Your words have penetrated into the vastness of the ocean. These words cannot be uttered by a mad person, a sorcerer or a poet. Extend your hand; I will pay allegiance to you to become a Muslim."
The Messenger of Allah (pbuh) extended his hand; Dimad caught his hand. Thus, the party of the polytheists lost a person and the Muslims won one more person.
Dimad bin Tha'laba was a person who was loved and respected by the people around him and by his tribe. He cured the most hopeless disorders and mental illnesses. Knowing the properties of Dimad, the Messenger of Allah (pbuh) said to Dimad when he extended his hand, "Shall I accept this allegiance also on behalf of your tribe?" Dimad answered without hesitation, "Yes, also on behalf of my tribe."
Dimad, who stayed with the Messenger of Allah (pbuh) for a while and learned the Quran from him, returned to his tribe called Azdu Shanua joyfully and happily. 
(We have not come across any information about the life of Dimad after this in our resources.)
Muslim, Jumua: 13, 46; Usdul-Ghaba, 3: 41.