1 Nephi 7:17-18
17. But it came to pass that I prayed unto the Lord, saying: O Lord, according to my faith that is in thee, wilt thou deliver me from the hands of my brethren; yea, even give me strength that I may burst these bands with which I am bound.
18 And it came to pass that when I had said these words, behold, the bands were loosed from off my hands and feet, and I stood before my brethren, and I spake unto them again.
Verse 17 can be read two ways. It can be seen as a prayer of fervent believing, or it can be seen as an exercise of priesthood power. The wording suggests the latter. If it is, then it tells us something important about Nephi. He is only a boy, but since he was not a descendant of Aaron, he did not have the Aaronic priesthood. But relationship with heaven—hearing the words spoken by God, being defended by angels, untying knots that ought to have remained tied tight—all these experiences are priesthood experiences. They suggest that this boy was exercising the power and authority of the Melchizedek priesthood. The questions associated with verse 22 are relevant to this point.