The death penalty is mandatory for a son who strikes his father or his mother. The word for "strike" or "smite" here, and throughout the passage, means "to attack with great force." A man who slapped his mother or father, for instance, would not necessarily have committed a capital crime. It would have to be something close to attempted murder: beating his father up, hitting him hard with an implement, trying to kill him, and the like. Ordinarily, assault is not punished by death (Exo. 21:18-19). But the divine sanction given parental authority explains the severity of the punishment. The Bible puts submission to any earthly authority under the fifth commandment. Thus, by extension, the death penalty for attempted murder can be applied to a man who attacks Church elders, civil magistrates, or policemen (cf. Deut. 17:12); and to a slave who attacks his master.
- James Jordan, The Law of the Covenant 103-04, 203 (1984), at http://www.garynorth.com/freebooks/: HTML, DjVu.