Ex. 19:5-6; Deut. 5:2-3
“Some have mistakenly supposed that the Ten Commandments were a part of the law of Moses. In fact, they are a part of the higher law or the fulness of the gospel. This is illustrated by their reiteration to us as part of the restoration of all things (see D&C 59:5-12). The Ten Commandments were a part of the fulness of the gospel as first given to Moses on Sinai. Though the higher priesthood and its ordinances were taken from Israel because of her transgressions, when Moses returned to Sinai to receive what we know as the law of Moses the Ten Commandments were retained as a part of Israel’s covenant with God.” (R. Millet and J. F. McConkie, Doctrinal Commentary on the Book of Mormon, 2:216)