D&C 8

To Oliver Cowdery, the Lord said -

"...verily, I say unto you, that assuredly as the Lord liveth, who is your God and your Redeemer, even so surely shall you receive a knowledge of whatsoever things you shall ask in faith, with an honest heart, believing that you shall receive..." (Doctrine and Covenants Section 8:1)

In this particular case, the Lord was referring to Oliver's desire to participate in translation and -

"...a knowledge concerning the engravings of old records, which are ancient, which contain those parts of my scripture of which has been spoken by the manifestation of my Spirit." (Doctrine and Covenants Section 8:1)

But it is clear that this requirement is to all men you desire "a knowledge of whatsoever things". To receive such knowledge, on must " ask in faith, with an honest heart, believing that your shall receive". This same principle is taught throughout the scriptures, that is -

"...if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you..." (Book of Mormon Moroni 10:4)

as this is done, He promises -

"...behold, I will tell you in your mind and in your heart, by the Holy Ghost, which shall come upon you and which shall dwell in your heart.
3 Now, behold, this is the spirit of revelation..." (Doctrine and Covenants Section 8:2 - 3)

Which the Lord explains is the same -

"...spirit by which Moses brought the children of Israel through the Red Sea on dry ground." (Doctrine and Covenants Section 8:3)

The same Spirit is promised to all those that ask in faith for -

"Remember that without faith you can do nothing; therefore ask in faith." (Doctrine and Covenants Section 8:10)

President J. Reuben Clark said -

“As I think about faith, this principle of power, I am obliged to believe that it is an intelligent force. Of what kind, I do not know. But it is superior to and overrules all other forces of which we know. . . .“[We] have had this great power given unto us, this power of faith. What are we doing about it? Can you, can we, do the mighty things that the Savior did? Yes. They have been done by the members of the Church who had the faith and the righteousness so to do. Think of what is within your power if you but live the Gospel, if you but live so that you may invoke the power which is within you.” (In Conference Report, Apr. 1960, p. 21.)

But when asking in faith, the Lord warns and counsels -

"...Trifle not with these things; do not ask for that which you ought not." (Doctrine and Covenants Section 8:10)