Albert Barnes Commentary Daniel 3:15

"Now if ye be ready that at what time ye hear the sound of the cornet, flute, harp, sackbut, psaltery, and dulcimer, and all kinds of music, ye fall down and worship the image which I have made, [well]: but if ye worship not, ye shall be cast the same hour into the midst of a burning fiery furnace; and who is that god that shall deliver you out of my hands?" — Daniel 3:15 (ASV)

Now, if you are ready, that at whatever time ... - At the very time; on the very instant. It would seem probable from this that the ceremonies of the consecration of the image were prolonged for a considerable period, so that there was still an opportunity for them to unite in the service if they were willing. The supposition that such services would be continued through several days is altogether probable, and accords with what was usual on festival occasions. It is remarkable that the king was willing to give them another trial, to see whether they were disposed or not to worship the golden image. To this he might have been led by the concern that they had not understood the order, or that they had not properly considered the subject; and possibly by respect for them as faithful officers, and for their countryman Daniel.

Moreover, there seems to have been in the heart of this monarch, with all his pride and passion, a readiness to do justice, and to provide an opportunity for a fair trial before he resorted to extreme measures. See Daniel 2:16, Daniel 2:26, Daniel 2:46–47.

And who is that God that shall deliver you out of my hands? - That is, he either supposed that the God whom they worshipped would not be “able” to deliver them, or that he would not be “disposed” to do it. It was a boast of Sennacherib, when he waged war against the Jews, that none of the gods of the nations which he had conquered had been able to rescue the lands over which they presided, and he argued from these premises that the God whom the Hebrews worshipped would not be able to defend their country: Hath any of the gods of the nations delivered his land out of the hand of the king of Assyria?

Where are the gods of Hamath, and of Arphad? where are the gods of Sepharvaim? and have they delivered Samaria out of my hand? Who are they among all the gods of these lands, that have delivered their land out of my hand, that the Lord should deliver Jerusalem out of my hand? (Isaiah 36:18–20). Nebuchadnezzar seems to have reasoned in a similar manner, and with a degree of vain boasting that strongly resembled this, calling their attention to the certain destruction which awaited them if they did not comply with his demand.