on the day. Same as Genesis 2:17. Here several days must have elapsed.
shalt surely die. Figure of speech Polyptoton. App-6. Hebrew "a dying thou shalt die", as in Genesis 2:17.
thine own head. thyself, "head" being put by Fig, Synecdoche (of the Part) for the whole person. App-6. See note on 1 Kings 2:9.