When people would seek a fatwa from Hazrat Umar (Radhiyallahu anhu) on some issue, he would query whether the episode had actually transpired or whether it was merely an assumed occurrence. If it was a real episode, he would answer. If not, he would refrain from answering and reprimand the person for indulgence in futility.
(Malfoozaat of Moulana Ashraf Ali Thanwi Rahmatullahi alaih)