How do people practice black magic? Surely it is up to Allah if any bad thing happens to us not the magician?

BLACK MAGIC
Q What is the reality of jadoo (black magic)? Does it really have any effect on people? Many people resort to the use of ta'weez (amulets) to counter the alleged effects of the jadoo. Is this permissible and does it have any effect?

A Sihr (the Arabic term for jadoo or black magic) is a reality. In this world of cause and effect, Allah Ta'ala has placed various effects in various things. The effects become apparent only with the will of Allah Ta' ala. Hence just as poison has the effect of killing, and the antidote of the poison has the consequence of countering its effects, so too does sihr have its effect. At times the effects become apparent upon the person who is afflicted and at times he suffers absolutely no harm. However to practice sihr is totally haraam and a major sin. If a person regards this practice as permissible, it results in kufr.
To counter these effects one should resort to the recitation of various verses of the Qur'an (such as Surah Falaq and Surah Naas). The use of ta' weez is not any ibadah (worship). It is simply a form of treatment and a type of "alternative medicine." It is thus permissible to resort to it with the following conditions: 1. Its use is for some permissible purpose (eg. to treat an ailment, etc.), not for anything impermissible (eg. to cause harm to anyone). 2. No words of kufr or shirk must be written therein. 3. The ta' weez must not be regarded as having any independent effect. Rather, its benefit is only with the will of Allah Ta'ala, as is the case with any other form of medication.
At times people under the effects of sihr utter various things in a trance-like state. To believe any such utterance, or to act upon what was heard, is totally forbidden. Such statements are devoid of any truth. To harbour suspicion or level accusations against people on the basis of such utterances is tantamount to slander, which is an extremely serious major sin.
While sihr and its like is a reality and many are truly afflicted by it, it is often made a scapegoat, even where it does not exist, for every trivial thing. This is highly repugnant. It becomes a means of creating baseless suspicion and breeding totally unfounded doubts on innocent people. One should refrain from heaping the blame of every little thing on sihr. Instead one should ponder over the true reason of these problems. Many problems are the direct result of our sins. Furthermore, the home wherein there is no salaah, recitation of the Qur'an, zikr, etc. will naturally be devoid of barakah. At the same time the T.V., videos, music, photographs of animate objects, etc. are inviting the wrath of Allah Ta'ala and preventing the entry of the angels into the home. Besides problems, what else can then be expected. Such problems will not be solved by any ta'weez. The solution is to refrain from sin, become obedient to Allah Ta'ala, recite Qur'an in the home, and literally fling out the T.V., videos, music, etc. This will solve the problems.
One more aspect in this regard needs to be rectified. Many people have more trust upon the ta'weez than they have upon dua. This is an extremely detestable attitude. The ta'weez is merely a form of permissible treatment (with the aforementioned conditions) whereas dua is a great Ibadah. One should therefore have greater conviction in dua. One should aquaint oneself with the aspects that enhance the acceptability of dua and adopt them while at the same time totally refrain from all such things that become an obstacle for the acceptance of duas.
The same is the case with aamils (those who treat people afflicted by sihr, etc.). Having the ability to treat people by means of ta'weez, etc. is not directly linked to being pious or religious. Just as there are pious doctors as well as irreligious ones, likewise there are some very pious saintly aamils and many extremely unscrupulous ones also. If one requires the treatment of an aamil, one should be careful in one's choice. At the same time the aamil should not be regarded as anything more than a doctor. Neither can he cure one nor does he know the unseen. One's conviction should be on Allah Ta'ala ONLY. Shifa (cure) comes from Allah Ta'ala ONLY.

Al-Haadi vol.2