Good then...
Whose will did God Himself come down from heaven to do, if not his own???
Once again! He laid aside His power as God and became the servant, while never ceasing to be God.
He was telling the Jews that the God they claimed to serve had sent Him.
I think it would help you to know that Christ became a total servant in His humanity.
All the miracles He performed were not of His power, He had cast that aside, it was all done by the Holy Spirit through Him.
He only knew what the Holy Spirit revealed to Him, He was totally and completely led by the Spirit.
Which of course is our example of how to live this Christian life, and the only way that will please the Father.