Although he was a son, he learned obedience through what he suffered. And being made perfect, he became the source of eternal salvation to all who obey him, being designated by God a high priest after the order of Melchizedek. (Hebrews 5:8-10)
Another way to say that God is omniscient is to say that He cannot learn anything. But these verses are saying that Jesus learned obedience and was made perfect. This even seems to do against the immutability of God. What does it mean for Him to learn something? I think that it cannot be more than what He knew before, but somehow less. He was tempted only because He was given the option of being separated from Himself. This might be something that I can never fully understand, but I am thankful that Jesus is my priest who knows what I feel, but never sinned. Father, thank you for being my priest. Without Jesus, there is no way for me to come to you. Thank you that you love me so much that although you already know everything, you learned obedience. Please teach me obedience that I will bring glory to your name.