And there came in two men, children of Belial, and sat before him: and the men of Belial witnessed against him, even against Naboth, in the presence of the people, saying, Naboth did blaspheme God and the king. Then they carried him forth out of the city, and stoned him with stones, that he died. (1 Kings 21:13)
It appears from 2 Kings 9:26 that not only Naboth but also his sons were stoned. When Achan was put to death his sons and daughters were stoned with him (Joshua 7:24, 25). With Naboth’s sons out of the way there would be no heirs to law claim to the vineyard. The crime thus became doubly heinous.