It is given in Khasaais-e-Kubra that Uthman Bin Abul A’as says: I complained to the Holy Prophet (Sallallahu alaihi wa sallam) that I cannot remember the Holy Quran. He (Sallallahu alaihi wa sallam) said: The reason for this is a devil named Khinzab. O Uthman, you draw close to me. Then He placed His hand on my chest and said: O devil! Leave the bosom of Uthman. He says: After this, whatever I heard, I would remember it.
Here the doctors might be surprised that the reasons for weakness of memory are different and this Hadith establishes that even the devil can cause people to forget. This surprise cannot be dispelled until and unless one has absolute belief in the power of Allah. This is the limit of obstinacy that based on personal knowledge one ignores the knowledge of others. The intellectuals are always reflecting over the cause of diseases and because of this, a stockpile of new discoveries is gained by them.
It is given in Khasaais-e-Kubra that Jareer (May Allah be well pleased with him) says: Whenever I would mount a horse, I would fall down. I described this to the Holy Prophet (Sallallahu alaihi wa sallam). He tapped my chest with His hand said: Allahumma Thabbit Waj‘alhu Hadiyanw Wa Mahdiyya. He says I never fell from my horse after this.
If a soldier expresses this condition before a king, then he will be the victim of royal wrath, but how candidly did Jareer (May Allah be well pleased with him) tell all this to the Holy Prophet (Sallallahu alaihi wa sallam)! And how wonderfully did the Holy Prophet (Sallallahu alaihi wa sallam) treat it!
The fact is that the Companions knew that the Holy Prophet (Sallallahu alaihi wa sallam) has the authority to do what He wants. For this reason, they would present before Him such diseases and needs that except Allah no one else could treat or fulfill them. As per their belief, the Holy Prophet (Sallallahu alaihi wa sallam) would also fulfill their needs so that their beliefs hold fast and their faith is strengthened. If it were not so, then the Holy Prophet (Sallallahu alaihi wa sallam) would have straight away told him: Falling off from a horse is innate to you, what can I do about it? On the contrary, by tapping his chest with His hand, the Holy Prophet (Sallallahu alaihi wa sallam) established that Allah has placed such power in my hand that I can remove this complaint and this is what happened. He would always be mounted in battles and impress one and all with his horse riding.
In Khasaais-e-Kubra, it has been narrated on the authority of Abbas (May Allah be well pleased with him) that one lady brought her son to the Holy Prophet (Sallallahu alaihi wa sallam) and said: O Prophet of Allah (Sallallahu alaihi wa sallam)! He suffers from lunacy. When we have food in the morning and night, his condition is aggravated and he troubles us. The Holy Prophet (Sallallahu alaihi wa sallam) caressed his chest with His hand and said a prayer. Immediately, the child coughed up something black and he was cured.
A doctor has to find out the signs, symptoms and then prescribe something. Here, there is no need for all that. He (Sallallahu alaihi wa sallam) would just caress with His hand and the diseased would be cured, regardless of the cause of the disease.
[Excerpted from Maqasid Ul Islam, Vol. 9]