The insertion of a pointed stake into a human body. It was likely practiced in ancient Egypt, Assyria, Babylonia, Persia, and possibly also in Israel. There are, however, many problems in understanding what impalement means in the Old Testament. Its meaning varies in different passages.
Greek documents can be unclear. They use the same word for both impalement and crucifixion. (In crucifixion, they fasten the body to a stake rather than puncturing it.) It is also not clear whether the impalement is done to a living body or to a corpse. Probably, both types of impalement were used. The former was for execution. The latter was to expose the corpse to the elements, beasts, and disgrace. Furthermore, it is not clear to what extent “hanging” in the Old Testament refers to impalement. Its typical use with "on" (not "from") may suggest a desire for some form of impalement.
Mesopotamian sources shed some light on impalement. It was a method of execution. One case was for a woman who caused her husband's death (Code of Hammurabi 153). Another was for a woman who aborted herself (Middle Assyrian Laws 53). The latter law states that the woman should be impaled, regardless of whether she survived the abortion. Assyrian kings claimed to have hung war captives on stakes. Assyrian art shows impaled bodies in battle scenes. The stake could be pushed up into the chest, with the body facedown, or between the legs, with the body upright.
Darius’s decree in Ezra 6:11 to rebuild the Jerusalem temple allowed for punishing violators, possibly by impalement. If the expression “hang on a tree [stake]” (for instance, Genesis 40:19; Deuteronomy 21:22; Joshua 8:29; 10:26; Esther 2:23) refers to impalement, a corpse was being impaled (Joshua 10:26). This interpretation also applies to Deuteronomy 21:22. There, the victim is first killed and then "hung." The similarity to Christ's crucifixion (Galatians 3:13) is the disgrace, not the method. Other possible examples of impalement are found in 2 Samuel 4:12 and 21:6–13.