Matthew 22:19

“Show me the tribute money.” And they brought to him a denarius.'

Then He bade them to show Him the tribute money, that is the coin in which they would pay the tribute. And as He anticipated they brought Him a denarius. Most religiously minded Jews sought to avoid carrying a denarius, firstly because it bore the graven image of the emperor, something forbidden by the ten commandments, and secondly because it had written on it certain superscriptions. On one side was engraved, ‘Tiberius Caesar, son of the divine Augustus' and on the other side ‘Pontifex Maximus' (high priest - of Roma and the Roman gods). Both would be seen as blasphemous. Thus they would grudgingly use it to pay their taxes, but would seek to avoid it on other occasions whenever they could.

‘They brought Him --.' This may suggest that the particular questioners did not have one themselves but had to obtain one, probably from one of the Herodians, or from someone in the listening crowd. By this time the crowd would have recognised the importance of the question and would be paying great attention. They probably did not recognise that it was a trap and would therefore expect the prophet to violently denounce the paying of tribute.