Adam Clarke on 1 Kings 2:37

Thy blood shall be upon thine own head - Thou knowest what to expect; if thou disobey my orders thou shalt certainly be slain, and then thou shalt be considered as a self-murderer; thou alone shalt be answerable for thy own death. Solomon knew that Shimei was a seditious man, and he chose to keep him under his own eye; for such a man at large, in favorable circumstances, might do much evil. His bitter revilings of David were a sufficient proof.