Charles Ellicott Commentary 1 Kings 21:8

"So she wrote letters in Ahab`s name, and sealed them with his seal, and sent the letters unto the elders and to the nobles that were in his city, [and] that dwelt with Naboth." — 1 Kings 21:8 (ASV)

Sealed them with his seal — with the name, or token, of the king, engraved on stone, and impressed on a lump of clay attached to the letter. The sealing (as the modern sense of “signature” implies) was the pledge of authenticity and authority. (Nehemiah 9:38; Nehemiah 10:1; Esther 3:10; Esther 3:12; Daniel 6:17; and so on.) The use of the seal—ordinarily worn or carried on the person—implies Ahab’s knowledge that something is being done in his name, into which he takes care not to inquire.

In his city. — This would be most naturally interpreted as Jezreel; but if Naboth dwelt or sojourned at Samaria, it may be Samaria. Jezebel naturally desires that neither Ahab nor she herself, though close at hand, should appear in the matter; but gives the necessary authority in writing, because without it the deed could not be done.