Ruling on praying behind one who claims to read palms and coffee cups
Question

                Is it permissible to pray behind a fortune-teller? I am sure he claims that he reads palms and coffee cups. He leads the prayer when the salaried imam is for some reason absent. There is no one else who has memorised the Quraan but him.
Praise be to Allah.It is not permissible to 
    pray behind one who claims to have knowledge of the unseen by reading coffee 
    cups or palms or anything else, because claiming to have knowledge of the 
    unseen is kufr. 
Shaykh Ibn Baaz (may Allaah 
    have mercy on him) was asked: Is it permissible to pray behind an imam who 
    is a charlatan and a liar, knowing that some of them recite Qur’aan well? 
He replied: 
If the imam is a charlatan 
    who claims to have knowledge of the unseen or who does false and evil 
    things, then it is not permissible to appoint him as an imam or to pray 
    behind him, because the one who claims to have knowledge of the unseen is a 
    kaafir – we ask Allaah to keep us safe and sound. Allaah says 
    (interpretation of the meaning): 
“Say: None in the 
    heavens and the earth knows the Ghayb (Unseen) except Allaah, nor can they 
    perceive when they shall be resurrected”
[al-Naml 27:65]
The same applies to the one 
    who practices witchcraft – he comes under the same ruling as the kuffaar, 
    because Allaah says (interpretation of the meaning): 
“They followed what the 
    Shayaateen (devils) gave out (falsely of the magic) in the lifetime of 
    Sulaymaan (Solomon). Sulaymaan did not disbelieve, but the Shayaateen 
    (devils) disbelieved, teaching men magic and such things that came down at 
    Babylon to the two angels, Haaroot and Maaroot, but neither of these two 
    (angels) taught anyone (such things) till they had said, ‘We are for trial, 
    so disbelieve not (by learning this magic from us).’”
[al-Baqarah 2:102]

    But if he commits some sins but does not do any of the 
    actions that constitute kufr such as witchcraft or claiming to have 
    knowledge of the unseen, but he does commit some sins, then prayers offered 
    behind him are valid, but it is better to look for another imam who is of 
    good character and is righteous, so as to be on the safe side with regard to 
    your religious commitment and so as to avoid going against those scholars 
    who say that it is not permissible to pray behind him. Sinners should not be 
    taken as imams but when they are imams, prayers offered behind them are 
    valid, because the people may be tested with them and it may be necessary to 
    pray behind them. But as for the one who calls on someone other than Allaah 
    or seeks the help of the dead and asks them for support, no one should pray 
    behind him, because by doing those things he is a kaafir, as these are the 
    actions of the mushrikeen whom the Prophet  (peace and blessings of 
    Allaah be upon him) fought in Makkah and elsewhere. We ask Allaah to set the 
    affairs of the Muslims straight and to enable them to understand their 
    religion properly, and appoint the best of them in charge of their affairs, 
    for He is All-hearing, Ever Near. 

    End quote from Majmoo’ Fataawa Ibn Baaz (9/278). 

    The person asked about here should be advised and the truth 
    should be explained to him, and the regular imam should be informed about 
    him, so that he can prevent him leading the prayers in his absence. 

    And Allaah knows best.