Praying behind someone who makes amulets
Question

                Is it permissible to pray behind an imaam who makes amulets for people, then if a  drought comes he tells the people to buy a ram or a cow, and to slaughter it and let the young boys eat it at the time of the drought, so that rain will come? Is it permissible to pray behind an imaam who makes vows and offers sacrifices to something or someone other than Allaah?
Praise be to Allah.Firstly: it is permissible to pray behind one who writes 
          amulets from the Qur’aan and prescribed du’aa’s, but he should not write 
          them, because it is not permissible to hang them on one’s body or elsewhere. 
          But if the amulets include anything that constitutes shirk, then you 
          should not pray behind the one who writes them. It should be explained 
          to him that this is shirk and the one who should do that (explain this) 
          is one who has knowledge of this matter. 
Making vows to anyone or anything other than Allaah is 
          shirk, and offering sacrifices to anyone or anything other than Allaah 
          is shirk, because Allaah says (interpretation of the meaning): 
“And 
          whatever you spend for spendings (e.g., in Sadaqah — charity for Allaah’s 
          Cause) or whatever vow you make, be sure Allaah knows it all
[al-Baqarah 2:270] 
“Say 
          (O Muhammad): “Verily, my Salaah (prayer), my sacrifice, my living, 
          and my dying are for Allâh, the Lord of the ‘Aalameen (mankind, jinn 
          and all that exists).
[al-An’aam 6:162] 
And because the Prophet  
          (peace and blessings of Allaah be upon him) said: “May Allaah curse 
          those who offer sacrifices to anyone or anything other than Allaah.”
Vows are also implied by the word “nusuki” 
          (in al-An’aam 6:162, translated here as “my sacrifice”). 
Secondly: It has 
          not been reported that the Prophet  
          (peace and blessings of Allaah be upon him) ever commanded anyone to 
          buy a ram or a cow to slaughter it and let the young boys eat it when 
          there was a drought, in order to make rain fall. What is prescribed 
          in such cases is Salaat al-Istisqaa’ (prayer asking for rain), du’aa’, 
          praying for forgiveness and giving in charity. The action described 
          in the question is a bid’ah (reprehensible innovation) which has no 
          basis in the pure sharee’ah of Islam. It was reported in a saheeh hadeeth 
          that the Prophet  (peace and blessings 
          of Allaah be upon him) said: “Whoever does an action that is not in 
          accordance with this matter of ours (i.e., Islam), will have it rejected.”
And Allaah is the source of strength. May Allaah bless 
          our Prophet Muhammad and his family and companions, and grant them peace.