Alma 22:17-18

17 And it came to pass that when Aaron had said these words, the king did bow down before the Lord, upon his knees; yea, even he did prostrate himself upon the earth, and cried mightily, saying:

18 O God, Aaron hath told me that there is a God; and if there is a God, and if thou art God, wilt thou make thyself known unto me, and I will give away all my sins to know thee, and that I may be raised from the dead, and be saved at the last day. And now when the king had said these words, he was struck as if he were dead.

The most beautiful, simple, faith-filled prayer I've ever heard.

(Apparently God thought it was pretty special too.)