Translation: While the imagery of sitting with Abraham, Isaac, and Jacob is clearly Jewish, the particular language is most closely tied to the New Testament rather than the Old. The only parallel from the Bible to this phrase in the Book of Mormon is found in Matthew:
Matt. 8:11 And I say unto you, That many shall come from the east and west, and shall sit down with Abraham, and Isaac, and Jacob, in the kingdom of heaven.
As has been noted before, this suggests that the translation process allowed Joseph the freedom of expressing the plate text in terms that were familiar to him, and his most familiar reference text was the New Testament rather than the Old Testament.