This idiom means the king was still in the act of speaking. Alternate translation: "While the king was still speaking" (See: [[rc://en/ta/man/translate/figs-idiom]])
This can be stated in active form. Alternate translation: "King Nebuchadnezzar, a decree went out against you that this kingdom no longer belongs to you" (See: [[rc://en/ta/man/translate/figs-activepassive]])