He said to his wife: If you check my mobile phone you are divorced
Question

                I said to my wife: If you check my mobile phone you are divorced. I am worried that she will check my mobile phone. What is the solution?.
Praise be to Allah.If a man says to his 
      wife: If you check my mobile phone you are divorced, the basic principle 
      is that a revocable divorce (talaaq) takes place if she checks it, and it 
      is not possible to cancel that. He has to warn his wife against checking 
      the mobile phone lest divorce occur. If she does check it, one revocable 
      divorce occurs and he may take her back during the ‘iddah. 
See the answer to question 
    no. 105438. 
Some scholars are of the 
    view – with regard to this basic issue – that if the husband’s intention is 
    to prevent his wife doing something, and he does not intend to divorce, then 
    it comes under the ruling on oaths (yameen), so he has to offer expiation 
    for breaking an oath (kafaarat yameen) if she does that, and it does not 
    count as a divorce. This is the view favoured by Shaykh al-Islam Ibn 
    Taymiyah (may Allah have mercy on him) and a number of scholars, and it is 
    the more correct view. See the answer to question no.
    82400. 
Each person knows his own 
    intention best, and Allah is watching over him, so it will not avail him 
    anything to deceive himself and claim that he did not intend to divorce at 
    the time he said it, if that was indeed his intention. 
And Allah knows best.