5:18 And it came to pass that Nephi and Lehi did preach unto the Lamanites with such great power and authority, for they had power and authority given unto them that they might speak, and they also had what they should speak given unto them--

 5:19 Therefore they did speak unto the great astonishment of the Lamanites, to the convincing them, insomuch that there were eight thousand of the Lamanites who were in the land of Zarahemla and round about baptized unto repentance, and were convinced of the wickedness of the traditions of their fathers.