Jamieson, Fausset and Brown on Matthew 12:38

38. Then certain of the scribes and of the Pharisees answered, saying, Master--"Teacher," equivalent to "Rabbi."

we would see a sign from thee--"a sign from heaven" (Lu 11:16); something of an immediate and decisive nature, to show, not that His miracles were real--that they seemed willing to concede--but that they were from above, not from beneath. These were not the same class with those who charged Him with being in league with Satan (as we see from Lu 11:15, 16); but as the spirit of both was similar, the tone of severe rebuke is continued.