Mark 8:11-13

When the Pharisees heard that Jesus had arrived, they came and started to argue with him. Testing him, they demanded that he show them a miraculous sign from heaven to prove his authority. When he heard this, he sighed deeply in his spirit and said, “Why do these people keep demanding a miraculous sign? I tell you the truth, I will not give this generation any such sign.” So he got back into the boat and left them, and he crossed to the other side of the lake.