John 2:18

What sign shewest thou unto us? (Ti shmeion deiknuei hmin;). They may have heard of the "sign" at Cana or not, but they have rallied a bit on the outside of the temple area and demand proof for his Messianic assumption of authority over the temple worship. These traders had paid the Sadducees and Pharisees in the Sanhedrin for the concession as traffickers which they enjoyed. They were within their technical rights in this question.