3 Nephi 7: 15-17

And it came to pass that Nephi---having been visited by angels and also the voice of the Lord, . . . and also being eye-witness to their quick return from righteousness unto their wickedness and abominations; Therefore, being grieved for the hardness of their hearts and the blindness of their minds---went forth among them in that same year, and began to testify, boldly, repentance and remission of sins through faith on the Lord Jesus Christ. And he did minister many things unto them; . . .  And Nephi did minister with power and with great authority.