Albert Barnes Commentary 1 Kings 21:10

"and set two men, base fellows, before him, and let them bear witness against him, saying, Thou didst curse God and the king. And then carry him out, and stone him to death." — 1 Kings 21:10 (ASV)

Sons of Belial - that is, “worthless persons” (Deuteronomy 13:13). Witnesses must be two in number according to the Law (Numbers 35:30; Deuteronomy 17:6; Deuteronomy 19:15).

The word translated as “blaspheme” is the one that commonly means “bless.” The opposite meaning of “cursing,” however, seems to be required here and in Job 1:5, 11 and Job 2:5. Perhaps the best explanation for this negative meaning is found in the practice of blessing as a salutation, not only upon meeting but also when taking leave (Genesis 47:7, 10). From this latter custom, the word came to mean “bidding farewell to,” and therefore “renouncing,” “casting off,” or “cursing.”

Carry him out and stone him - Naboth’s offense would be twofold, and in both cases capital. Blasphemy against God was punishable by death under the Law, and blasphemy against the king was a capital offense by custom (1 Kings 2:8; 2 Samuel 16:9; 2 Samuel 19:21). The punishment would be stoning, since the greater crime would absorb the lesser, and the Law made stoning the punishment for blasphemy against God. As stoning always took place outside the city , Jezebel told the elders to “carry Naboth out.”