Jamieson, Fausset and Brown on Hosea 7:6

6. they have made ready--rather, "they make their heart approach," namely their king, in going to drink with him.

like an oven--following out the image in Ho 7:4. As it conceals the lighted fire all night while the baker sleeps but in the morning burns as a flaming fire, so they brood mischief in their hearts while conscience is lulled asleep, and their wicked designs wait only for a fair occasion to break forth [Horsley]. Their heart is the oven, their baker the ringleader of the plot. In Ho 7:7 their plots appear, namely, the intestine disturbances and murders of one king after another, after Jeroboam II.