Matthew 12:38
"Then certain of the scribes and of the Pharisees answered, saying, Master, we would see a sign from thee."
Cross References (ranked by relevance)
For the Jews require a sign, and the Greeks seek after wisdom:
And others, tempting him, sought of him a sign from heaven.
Then answered the Jews and said unto him, What sign shewest thou unto us, seeing that thou doest these things?
Then said Jesus unto him, Except ye see signs and wonders, ye will not believe.
And when the people were gathered thick together, he began to say, This is an evil generation: they seek a sign; and there shall no sign be given it, but the sign of Jonas the prophet.
They said therefore unto him, What sign shewest thou then, that we may see, and believe thee? what dost thou work?