Charles Ellicott Commentary Daniel 3:19

"Then was Nebuchadnezzar full of fury, and the form of his visage was changed against Shadrach, Meshach, and Abed-nego: [therefore] he spake, and commanded that they should heat the furnace seven times more than it was wont to be heated." — Daniel 3:19 (ASV)

One seven times.— It is doubtful whether “seven” is used here as a round number or not. According to the Babylonian mythology, there were seven demons, named “Maskim,” who were the most formidable of the infernal powers. Perhaps the number “seven” has a reference to them, for the religious nature of the punishment favours the view that the overheating of the furnace was regarded as a religious act.

Than it was wont.— More correctly, than it was fitting. The improper heating of the furnace led to the death of the mighty men (Daniel 3:22).