The Prophet Joseph Smith warned: “Whenever you see a man seeking after a sign, you may set it down that he is an adulterous man” (History of the Church, 3:385).
He later recalled: “When I was preaching in Philadelphia, a Quaker called out for a sign. I told him to be still. After the sermon, he again asked for a sign. I told the congregation the man was an adulterer; that a wicked and adulterous generation seeketh after a sign; and that the Lord had said to me in a revelation, that any man who wanted a sign was an adulterous person. ‘It is true,’ cried one, ‘for I caught him in the very act,’ which the man afterwards confessed, when he was baptized” (History of the Church, 5:268).