Matthew 4:3

‘And the tempter came and said to him, “If You are the Son of God, command that these stones become bread.” '

Then He became conscious of a malevolent presence, probably speaking in His mind. For forty days and nights He had been considering the significance of the words at His baptism, and now came the challenge. ‘You are hungry. If you really are the Son of God look around you. See these flat white stones that look like bread. Did not God provide manna in the wilderness? Why do you not turn them into bread and feed yourself, ensuring your preservation for the sake of mankind? It is after all important that you keep yourself fit and well. And at the same time you will be able to prove to yourself what you can do. Turning these stones into bread can only give you greater confidence in God. It can only be for good. You have done well. Now reap your reward.'

Jesus would be aware of what John had said about God turning stones into the sons of Abraham. The thought may be, if God can consider doing that, what harm can there be in the Son of God turning stones into bread? But it was not the act that would be wrong. It would be  why it was done. Later He would turn a few small loaves into sufficient to feed a large crowd. But that would be in order to confirm that they were a new covenant community whom God promised to feed spiritually (Matthew 14:15; Matthew 15:32). Here, however, it would simply be in order to satisfy His own needs in a way not available to others. By it He would cease to be a man among men. He would fall at the first hurdle.