The Lord has repeatedly promised that whoever obeys him will be kept in his way: “...inasmuch as you keep my sayings you shall not be confounded in this world, nor in the world to come.” (D&C 93:52) For example, he has said that:
No weapon that is formed against thee shall prosper; and every tongue that shall rise against thee in judgment thou shalt condemn. This is the heritage of the servants of the Lord, and their righteousness is of me, saith the Lord. (Isaiah 54:17)
Here, what seems like a promise to a specific individual is actually, on a careful reading, explicitly offered to all who serve the Lord and who live what he teaches them.
The Lord taught that:
1 The works, and the designs, and the purposes of God cannot be frustrated, neither can they come to naught.
2 For God doth not walk in crooked paths, neither doth he turn to the right hand nor to the left, neither doth he vary from that which he hath said, therefore his paths are straight, and his course is one eternal round.
3 Remember, remember that it is not the work of God that is frustrated, but the work of men; (D&C 3)
He continued that we ought to lean into the promise that his purposes can’t be frustrated:
7 For, behold, you should not have feared man more than God. Although men set at naught the counsels of God, and despise his words—
8 Yet you should have been faithful; and he would have extended his arm and supported you against all the fiery darts of the adversary; and he would have been with you in every time of trouble. (D&C 3)
And why shouldn’t you trust that God can accomplish anything he wills? After all, he “knoweth all things.” (2 Nephi 2:24)