I do know that

1. Alma 5: 45
     45 And this is not all. Do ye not suppose that I know of these things myself? Behold, I testify unto you that I do know that these things whereof I have spoken are true. And how do ye suppose that I know of their surety?
2. Alma 7: 8
     8 Behold, I do not say that he will come among us at the time of his dwelling in his mortal tabernacle; for behold, the Spirit hath not said unto me that this should be the case. Now as to this thing I do not know; but this much I do know, that the Lord God hath power to do all things which are according to his word.
3. Alma 18: 25
     25 And he answered, and said unto him: I do not know what that meaneth.
4. Alma 29: 11
     11 Yea, and I also remember the captivity of my fathers; for I surely do know that the Lord did deliver them out of bondage, and by this did establish his church; yea, the Lord God, the God of Abraham, the God of Isaac, and the God of Jacob, did deliver them out of bondage.
5. Alma 34: 8
     8 And now, behold, I will testify unto you of myself that these things are true. Behold, I say unto you, that I do know that Christ shall come among the children of men, to take upon him the transgressions of his people, and that he shall atone for the sins of the world; for the Lord God hath spoken it.
6. Alma 36: 3, 30
     3 And now, O my son Helaman, behold, thou art in thy youth, and therefore, I beseech of thee that thou wilt hear my words and learn of me; for I do know that whosoever shall put their trust in God shall be supported in their trials, and their troubles, and their afflictions, and shall be lifted up at the last day.
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     30 But behold, my son, this is not all; for ye ought to know as I do know, that inasmuch as ye shall keep the commandments of God ye shall prosper in the land; and ye ought to know also, that inasmuch as ye will not keep the commandments of God ye shall be cut off from his presence. Now this is according to his word.