Does hesitating about stopping the prayer cancel it out?
Question

                If a person who is praying hears somebody knocking at the door and he hesitates about whether to interrupt his prayer or not, is the prayer invalidated?.
Praise be to Allah.
    Some scholars are of the view that the prayer is invalidated 
    even if he does not decide to cut it short, and some of the scholars said: 
    the prayer is not invalidated because of hesitation, because the basic 
    principle is that the intention remains valid and hesitation does not cancel 
    it out. This view is the correct one; so long as he has not decided to cut 
    short the prayer, then he is still in a state of prayer. End quote. 

    Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen 
    (12/449) 

    For more information please see the answer to question number
    93529 on our website. 

    And Allaah knows best.