3 Nephi 1:3

then he departed out of the land, and whither he went, no man knoweth; and his son Nephi did keep the records in his stead, yea, the record of this people.

Then he left the land, and no one knows where he went. His son Nephi kept the records in his place.

Then he left, and no one knows where he went. His son Nephi took over keeping the records—the history of our people.