Judges 9:14,15 - Joseph Benson’s Commentary on the Old and New Testaments

Then said all the trees unto the bramble, &c. Or thorn, fitly representing Abimelech, the son of a concubine, and a person of small use and great cruelty. If in truth ye anoint me king If you deal truly and justly in making me king. Then trust Then you may expect protection under my government. Devour the cedars Instead of protection, you shall receive destruction by me; especially you cedars, that is, nobles, such as the house of Millo, who have been most forward in this work. By this fable Jotham signified to the Shechemites that the most worthy men in Israel, figured by the olive, the fig-tree, and the vine, which bear the most useful and excellent fruits, had not aimed at kingly dominion over them; and that his father Gideon had even refused it, when offered to him. By the bramble, the most worthless of shrubs, accepting the offer of the trees to be their king, and calling to them to put their trust in its shadow, though by its nature it could afford no shadow or protection to them, he shows what a worthless choice they had made. The speech of the bramble represents how foolish Abimelech was, in imagining he should be able to maintain the authority of a king, as he could by no means, any more than the bramble, afford the shade or protection he had promised: and the threat of the bramble seems to indicate the cruelty of Abimelech's temper, that he would destroy the Shechemites, if he found them unfaithful.