John Gill Commentary Daniel 3:9

"They answered and said to Nebuchadnezzar the king, O king, live for ever." — Daniel 3:9 (ASV)

They spoke and said to Nebuchadnezzar
Having got access to him, and within his hearing, they expressed themselves in the following manner: O king, live for ever ;
this they said to show their fidelity and hearty attachment to him, and their regard to his welfare, and the continuance of his life; and the rather to ingratiate themselves into his affections, and gain audience of him; (See Gill on Daniel 2:4).