Here is a list of all recorded prayers in the Book of Mormon.
30 ...O Lord, I will praise thee forever; yea, my soul will rejoice in thee, my God, and the rock of my salvation.
31 O Lord, wilt thou redeem my soul? Wilt thou deliver me out of the hands of mine enemies? Wilt thou make me that I may shake at the appearance of sin?
32 May the gates of hell be shut continually before me, because that my heart is broken and my spirit is contrite! O Lord, wilt thou not shut the gates of thy righteousness before me, that I may walk in the path of the low valley, that I may be strict in the plain road!
33 O Lord, wilt thou encircle me around in the robe of thy righteousness! O Lord, wilt thou make a way for mine escape before mine enemies! Wilt thou make my path straight before me! Wilt thou not place a stumbling block in my way—but that thou wouldst clear my way before me, and hedge not up my way, but the ways of mine enemy.
34 O Lord, I have trusted in thee, and I will trust in thee forever. I will not put my trust in the arm of flesh; for I know that cursed is he that putteth his trust in the arm of flesh. Yea, cursed is he that putteth his trust in man or maketh flesh his arm.
35 Yea, I know that God will give liberally to him that asketh. Yea, my God will give me, if I ask not amiss; therefore I will lift up my voice unto thee; yea, I will cry unto thee, my God, the rock of my righteousness. Behold, my voice shall forever ascend up unto thee, my rock and mine everlasting God. Amen. (2 Nephi 4)
...O God, receive my soul. (Mosiah 17:19)
And now it came to pass that Alma took Helam, he being one of the first, and went and stood forth in the water, and cried, saying: O Lord, pour out thy Spirit upon thy servant, that he may do this work with holiness of heart. (Mosiah 18:12)
And Alma cried, saying: How long shall we suffer these great afflictions, O Lord? O Lord, give us strength according to our faith which is in Christ, even unto deliverance. And they broke the cords with which they were bound; and when the people saw this, they began to flee, for the fear of destruction had come upon them. (Alma 14:26)
And then Alma cried unto the Lord, saying: O Lord our God, have mercy on this man, and heal him according to his faith which is in Christ. (Alma 15:10)
And he began to cry unto the Lord, saying: O Lord, have mercy; according to thy abundant mercy which thou hast had upon the people of Nephi, have upon me, and my people. (Alma 18:41)
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.26 And he lifted up his voice to heaven, and cried, saying: O, how long, O Lord, wilt thou suffer that thy servants shall dwell here below in the flesh, to behold such gross wickedness among the children of men? (Alma 22:18)
27 Behold, O God, they cry unto thee, and yet their hearts are swallowed up in their pride. Behold, O God, they cry unto thee with their mouths, while they are puffed up, even to greatness, with the vain things of the world.
28 Behold, O my God, their costly apparel, and their ringlets, and their bracelets, and their ornaments of gold, and all their precious things which they are ornamented with; and behold, their hearts are set upon them, and yet they cry unto thee and say—We thank thee, O God, for we are a chosen people unto thee, while others shall perish.
29 Yea, and they say that thou hast made it known unto them that there shall be no Christ.
30 O Lord God, how long wilt thou suffer that such wickedness and infidelity shall be among this people? O Lord, wilt thou give me strength, that I may bear with mine infirmities. For I am infirm, and such wickedness among this people doth pain my soul.
31 O Lord, my heart is exceedingly sorrowful; wilt thou comfort my soul in Christ. O Lord, wilt thou grant unto me that I may have strength, that I may suffer with patience these afflictions which shall come upon me, because of the iniquity of this people.
32 O Lord, wilt thou comfort my soul, and give unto me success, and also my fellow laborers who are with me—yea, Ammon, and Aaron, and Omner, and also Amulek and Zeezrom, and also my two sons—yea, even all these wilt thou comfort, O Lord. Yea, wilt thou comfort their souls in Christ.
33 Wilt thou grant unto them that they may have strength, that they may bear their afflictions which shall come upon them because of the iniquities of this people.
34 O Lord, wilt thou grant unto us that we may have success in bringing them again unto thee in Christ.
35 Behold, O Lord, their souls are precious, and many of them are our brethren; therefore, give unto us, O Lord, power and wisdom that we may bring these, our brethren, again unto thee. (Alma 31)
4 For he said: Thou art merciful, O God, for thou hast heard my prayer, even when I was in the wilderness; yea, thou wast merciful when I prayed concerning those who were mine enemies, and thou didst turn them to me.
5 Yea, O God, and thou wast merciful unto me when I did cry unto thee in my field; when I did cry unto thee in my prayer, and thou didst hear me.
6 And again, O God, when I did turn to my house thou didst hear me in my prayer.
7 And when I did turn unto my closet, O Lord, and prayed unto thee, thou didst hear me.
8 Yea, thou art merciful unto thy children when they cry unto thee, to be heard of thee and not of men, and thou wilt hear them.
9 Yea, O God, thou hast been merciful unto me, and heard my cries in the midst of thy congregations.
10 Yea, and thou hast also heard me when I have been cast out and have been despised by mine enemies; yea, thou didst hear my cries, and wast angry with mine enemies, and thou didst visit them in thine anger with speedy destruction.
11 And thou didst hear me because of mine afflictions and my sincerity; and it is because of thy Son that thou hast been thus merciful unto me, therefore I will cry unto thee in all mine afflictions, for in thee is my joy; for thou hast turned thy judgments away from me, because of thy Son. (Alma 33)
Now, as my mind caught hold upon this thought, I cried within my heart: O Jesus, thou Son of God, have mercy on me, who am in the gall of bitterness, and am encircled about by the everlasting chains of death. (Alma 36:18)
9 After this manner therefore pray ye: Our Father who art in heaven, hallowed be thy name.
10 Thy will be done on earth as it is in heaven.
11 And forgive us our debts, as we forgive our debtors.
12 And lead us not into temptation, but deliver us from evil.
13 For thine is the kingdom, and the power, and the glory, forever. Amen. (3 Nephi 13)
And it came to pass that when they had knelt upon the ground, Jesus groaned within himself, and said: Father, I am troubled because of the wickedness of the people of the house of Israel. (3 Nephi 17:14)
20 Father, I thank thee that thou hast given the Holy Ghost unto these whom I have chosen; and it is because of their belief in me that I have chosen them out of the world.
21 Father, I pray thee that thou wilt give the Holy Ghost unto all them that shall believe in their words.
22 Father, thou hast given them the Holy Ghost because they believe in me; and thou seest that they believe in me because thou hearest them, and they pray unto me; and they pray unto me because I am with them.
23 And now Father, I pray unto thee for them, and also for all those who shall believe on their words, that they may believe in me, that I may be in them as thou, Father, art in me, that we may be one. (3 Nephi 19)
28 Father, I thank thee that thou hast purified those whom I have chosen, because of their faith, and I pray for them, and also for them who shall believe on their words, that they may be purified in me, through faith on their words, even as they are purified in me.
29 Father, I pray not for the world, but for those whom thou hast given me out of the world, because of their faith, that they may be purified in me, that I may be in them as thou, Father, art in me, that we may be one, that I may be glorified in them. (3 Nephi 19)
18 And it came to pass that the brother of Jared cried unto the Lord, saying: O Lord, I have performed the work which thou hast commanded me, and I have made the barges according as thou hast directed me.
19 And behold, O Lord, in them there is no light; whither shall we steer? And also we shall perish, for in them we cannot breathe, save it is the air which is in them; therefore we shall perish. (Ether 2)
And he cried again unto the Lord saying: O Lord, behold I have done even as thou hast commanded me; and I have prepared the vessels for my people, and behold there is no light in them. Behold, O Lord, wilt thou suffer that we shall cross this great water in darkness? (Ether 2:22)
2 O Lord, thou hast said that we must be encompassed about by the floods. Now behold, O Lord, and do not be angry with thy servant because of his weakness before thee; for we know that thou art holy and dwellest in the heavens, and that we are unworthy before thee; because of the fall our natures have become evil continually; nevertheless, O Lord, thou hast given us a commandment that we must call upon thee, that from thee we may receive according to our desires.
3 Behold, O Lord, thou hast smitten us because of our iniquity, and hast driven us forth, and for these many years we have been in the wilderness; nevertheless, thou hast been merciful unto us. O Lord, look upon me in pity, and turn away thine anger from this thy people, and suffer not that they shall go forth across this raging deep in darkness; but behold these things which I have molten out of the rock.
4 And I know, O Lord, that thou hast all power, and can do whatsoever thou wilt for the benefit of man; therefore touch these stones, O Lord, with thy finger, and prepare them that they may shine forth in darkness; and they shall shine forth unto us in the vessels which we have prepared, that we may have light while we shall cross the sea.
5 Behold, O Lord, thou canst do this. We know that thou art able to show forth great power, which looks small unto the understanding of men. (Ether 3)
O God, the Eternal Father, we ask thee in the name of thy Son, Jesus Christ, to bless and sanctify this bread to the souls of all those who partake of it; that they may eat in remembrance of the body of thy Son, and witness unto thee, O God, the Eternal Father, that they are willing to take upon them the name of thy Son, and always remember him, and keep his commandments which he hath given them, that they may always have his Spirit to be with them. Amen. (Moroni 4:3)
O God, the Eternal Father, we ask thee, in the name of thy Son, Jesus Christ, to bless and sanctify this wine to the souls of all those who drink of it, that they may do it in remembrance of the blood of thy Son, which was shed for them; that they may witness unto thee, O God, the Eternal Father, that they do always remember him, that they may have his Spirit to be with them. Amen. (Moroni 5:2)