A large amount of money was stolen from the house of my friends. Some people told them that there was a person who could return what had been stolen from them. They went to that person and he showed them, on the surface of some water that he had, the thief and the place where he had hidden the money. Thus, they had the stolen money returned without any loss. I told my friend (who was one of these friends) that this was an act of sorcery, but she said that they had not harmed anyone and that they merely retrieved their money, so why is this prohibited?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Certainly, the person to whom your friend’s family went to was a sorcerer because he showed them the thief and the place of the stolen money on water, and this could only be done by a sinful sorcerer. 

The definition of sorcery, according to Imaam Al-Jassaas, who was a follower of the Hanafi School, is everything that is brought about with an unknown cause, unreal appearance, deception in nature, or camouflaged effects. 

The sorcerer could not have known the place of the stolen money except with help from Jinn. Jinns would not help or serve him, or obey his orders, unless he had committed prohibitions and acts of apostasy in order to please them. 

Shaykh As-Sa‘di said sorcery is considered an act of apostasy for two reasons:

1-      The using of devils and depending on them or, even worse, the sorcerer may offer the devils some acts which they love for them to serve him in response and respond to his requests.

2-      The claim that the sorcerer knows matters of the unseen and his allegation that he shares knowledge of Allaah the Almighty with Him

Thus, it is prohibited for any Muslim to seek the help of sorcerers or to believe them, because the Prophet, sallallaahu ‘alayhi wa sallam, described those who soothsay and those for whom soothsaying is done, as well as sorcerers and those who seek sorcery as not being Muslims.  [Al-Munthiri]

It was also narrated on the authority of Ibn Mas‘ood that the Prophet, sallallaahu ‘alayhi wa sallam, said that whoever went to a soothsayer, fortune teller or sorcerer and believed him has thereby disbelieved in what was revealed to Muhammad, sallallaahu ‘alayhi wa sallam.  [At-Tabaraani in Al-Kabeer and Al-’Awsat, Ibn Abi Shaybah in his Musannaf, Al-Bayhaqi in As-Sunan Al-Kubra and Abd-Ar-Razzaaq in his Musannaf]

The Prophet, sallallaahu ‘alayhi wa sallam, also mentioned that whoever goes to a diviner (like the person who told these friends about the place where the stolen money was) and seeks advice from him, Allaah will not accept Salah (prayer) from him for 40 days.  [Muslim]

The allegation that that the owners of the stolen money did no harm by going to this sorcerer is incorrect, because this is considered encouragement of and support for that sorcerer, which is certainly prohibited because sorcery is a major sin. Allaah the Almighty Says (what means): {But do not cooperate in sin and aggression}[Quran 5:2]

Moreover, this behavior causes sorcery to spread and become stronger within society, and this is a terribly heinous form of evil.  Furthermore, it impedes legitimate ways of catching criminals and belittles science and serious work that is based on evidence and real material proof. A Muslim should not place his personal interests above society's best interests. Also, soothsayers, diviners and sorcerers rarely speak the truth. 

And Allaah Knows best.