Jamieson, Fausset & Brown, on Judg 3:19

“Then returning from Galgal, where the idols were, be said to the king: I have a secret message to thee, O king. And he commanded silence: and all being gone out that were about him,”

“quarries--rather, "graven images" (Deu 7:25; Jer 8:19; Jer 51:52); statues of Moabite idols, the sight of which kindled the patriotic zeal of Ehud to avenge this public insult to Israel on its author. I have a secret errand unto thee, O king: who said, Keep silence--"Privacy"--a signal for all to withdraw.”

Imported from an open dataset — not yet checked against the printed edition.