He made the divorce of his wife conditional upon her doing something then he gave her permission to do it
Question

                My wife wanted to do something, and at that time I was angry so I said to her: If you do this thing then you are divorced, because it was not the right time for her to do that thing. After a little time passed, and after my anger abated, I gave her permission to do that thing, and when the time came to do it, she did it. Has divorce taken place, or did my allowing her to do it after that cancel it out?.
Praise be to Allah.
      The fact that you gave her permission does not cancel out 
      the divorce which you swore would take place or that you made conditional 
      upon this stipulation that you mention. Going back on your word does not 
      help you at all, and the divorce remains in effect, if she did what you 
      wanted to prevent her from doing. If what you intended by divorce was only 
      to stop her doing it and you did not intend to make her divorce 
      conditional upon it, then you have to offer expiation for breaking an oath 
      (kafaarat yameen), because this is the same as an oath. 

    But if your intention behind what you mentioned was to make 
    divorce conditional upon her doing this thing, then divorce has taken place, 
    if she did that on which it was made conditional. 

    If there were no previous divorces after which this would 
    bring the total to three, then it is a revocable divorce and the husband has 
    the right to take her back so long as the ‘iddah has not yet ended. But if 
    there were previous divorces and this is the third, then it is an 
    irrevocable divorce and she is not permissible to him until she has been 
    married to another husband. End quote. 

    And Allah knows best.