In verse 7 Mormon tells us that the Spirit has told him to incorporate the small plates of Nephi in his own record. In verse 5 and 6 Mormon describes the rather complicated procedure he will use to achieve this. Apparently he is going to stack the small plates on top of the abridgment he has already written. Then he will finish his record on new plates which he will pile on top of the small plates of Nephi.
We know from the Omni 1:30 that the small plates were already "full;" so we conclude that when Mormon says he will complete his record "upon" the small plates, it means that additional plates will be constructed on which he will need to inscribe the rest of his record, and these will be piled on top of the small plates and then bound together in one volume. Verse 6 bears out this deduction. Mormon says he is combining these plates with the plates of his own record, and in verse 7 Mormon says he is doing this for a wise purpose. He does not know what the purpose is, however. Only the Lord knows. Mormon simply follows the instructions because he knows his task is to simply follow the word of the Lord.
Before we leave these three verses, it will be recalled that in verse 5 Mormon said he was going to complete the remainder of his abridgment from the plates of Nephi. This has reference to the large plates of Nephi, which contained the comprehensive secular history of the Nephites during nearly 1,000 years, from 600 B.C. to 385 A.D.In verse 5 Mormon says the available records are so voluminous that he cannot include even a hundredth part.
At the time of Mormon's writing in 385 A.D. the Lamanites were a most ferocious and degenerate people. Mormon therefore prays that they may eventually come to a knowledge of God and the redemption of Christ that they may once again be a delightsome people.