A man that hath set at nought Moses’ law dieth without compassion on the word of two or three witnesses:
Verse 28. He that despised Moses' law. That is, the apostate from the religion of Moses. It does not mean that in all cases the offender against the law of Moses died without mercy, but only where offences were punishable with death, and probably the apostle had in his eye particularly the case of apostasy from the Jewish religion.
For we know him that hath said,.... That is, God, whom the apostle and the Hebrews knew; not merely by the works of creation and providence, but by the Scriptures, which they were favoured with, and by which they were distinguished from the Gentiles, and by which they knew his being, nature, and perfections; particularly, that what he said he was able to perform, and...
Compare Heb 2:2-3; Heb 12:25. despised--"set at naught" [ALFORD]: utterly and heinously violated, not merely some minor detail, but the whole law and covenant; for example, by idolatry (Deu 17:2-7). So here apostasy answers to such an utter violation of the old covenant. died--Greek, "dies": the normal punishment of such transgression, then still in force.