Albert Barnes Commentary Judges 9:27-29

"And they went out into the field, and gathered their vineyards, and trod [the grapes], and held festival, and went into the house of their god, and did eat and drink, and cursed Abimelech. And Gaal the son of Ebed said, Who is Abimelech, and who is Shechem, that we should serve him? is not he the son of Jerubbaal? and Zebul his officer? serve ye the men of Hamor the father of Shechem: but why should we serve him? And would that this people were under my hand! then would I remove Abimelech. And he said to Abimelech, Increase thine army, and come out." — Judges 9:27-29 (ASV)

Seditious and lawless acts (Judges 9:25–26) now broke out into open rebellion. The rebellion matured at an idolatrous feast in the house of Baal-berith, during the vintage, when those present were excited with wine. They began to “curse Abimelech,” to speak insultingly of him, and to revile him (2 Samuel 19:21; Isaiah 8:21). Gaal, the son of Ebed, watching for an opportunity, immediately incited them to revolt from Abimelech’s dominion, offering himself as their captain. He also added a message of defiance to Abimelech, probably addressed to Zebul, who was present but too weak to resent it on the spot.

(Judges 9:27) Made merry - The word translated “merry” occurs only here and in Leviticus 19:24. Its etymology gives the sense of “praises” and “thanksgivings”; and its use in these two passages rather indicates that the fruits themselves which were brought to the House of God with songs of praise, and eaten or drunk with religious service, were so called. The thank offerings would be a portion of the new wine of the vintage which they had just gathered.

(Judges 9:28) Shechem is another designation of Abimelech. Sheehem means the son and heir of Sheehem, Abimelech’s mother being a Canaanite (Judges 9:18).