It is reported that the Messenger of Allah (S) was in Mecca, when some polytheists came and said: O Muhammad, our god is Hubal, he cures the sick, delivers the dead and heals our wounds. His Eminence (S) said: You lie. Hubal is not doing anything. On the contrary, Allah treats whatever He likes.
The polytheists did not like to hear this. They said: O Muhammad (S) we are afraid that Hubal would involve you in paralysis, leprosy and many other diseases for making a claim against him. His Eminence (S) said: He is helpless and unable to do anything. But yes, Almighty Allah is Omnipotent. He does whatever He likes.
The polytheists said: O Muhammad! Request your god whom you worship, and if there is no god except Him, to involve us in the above diseases. Then we will go to Hubal and request him to relieve us from this disease. So that you may know that Hubal is a partner of your god whom you point to. At that time Jibraeel Amin (a.s.) appeared and said: O Allah’s Messenger (S) imprecate for some of them and Ali may do for some others.
His Eminence (S) imprecated for twenty and Ali for ten person. They hardly reached their homes when they were struck with leprosy, paralysis and blindness. Their hands and feet separated from their bodies and except for their tongues and ears, no part of their bodies remained free of disease. When this happened, they were taken to Hubal and he was requested to give them health.
They said: These people fell into this because of the imprecation of Muhammad and Ali, so please cure them. By the power of Allah, Hubal spoke up: O enemies of Allah! I am unable to do anything. I swear by One Who appointed Muhammad to all creation and made him excel all prophets and apostles. If he imprecates for me also, each and every part of my body will break into small pieces and fly away in air and my sign will not be seen.
If Allah does this for me, my greatest part will be smaller than one-hundredth of a rye seed. When the polytheists heard this from Hubal, they came to the Prophet (S) helplessly, weeping and wailing and saying: All our hopes are dashed and no one can help us except you. Help us and pray to Allah to cure our men. They will never harm you in the future. His Eminence (S) said: They will become healthy just as they became ill.
I am responsible for twenty of them and ten are Ali’s responsibility. They brought twenty sick persons to the Prophet and ten to Ali (a.s.). His Eminence (S) told those twenty men to close their eyes and pray as follows: O Allah, for the sake of the status of this person, for whom You involved us in diseases, now for the sake of Muhammad and Ali (a.s.) and their purified progeny, cure us of these diseases and give us health.
In the same way, Ali (a.s.) asked the ten persons and they did as told, and the very moment they became healthy and stood up as if freed from a rope and no sign of disease as left and they became healthier than what they were before falling in that trouble. All the thirty men and a few friends of theirs accepted Islam while others were overpowered by wickedness.
Reference:Hayat Al-Qulub Vol. 2