Tribute penny

Denarius of the Emperor Tiberius, commonly referred to as "the Tribute Penny".
The Tribute Money, by Titian (1516), depicts Jesus being shown the tribute penny

The tribute penny was the coin that was shown to Jesus when he made his famous speech "Render unto Caesar..." The phrase comes from the King James Version of the gospel account: Jesus is asked, "Is it lawful to give tribute to Caesar, or not?" (Mark 12:14) and he replies, "bring me a penny, that I may see it" (Mark 12:15).