Passover is a special date in the Jewish calendar. In Jesus’ time, people traveled great distances to spend Passover in Jerusalem. Part of the Passover ritual involved sacrificing animals and paying a tax to the temple. Since this tax needed to be paid in local currency, people from other areas had to have their money changed. Those who made long journeys could not bring their own animals for sacrifice, so they bought them in Jerusalem.
Jesus, who was a Jew, went to Jerusalem at Passover time. Here is an account of his visit from the Bible.
As the Jewish Passover was near, Jesus went up to Jerusalem. In the temple precincts he came upon people engaged in selling oxen, sheep and doves, and others seated changing coins. He made a whip of cord and drove sheep and oxen alike out of the temple area, and knocked over the money-changers’ tables, spilling their coins. He told those who were selling doves: “Get them out of here! Stop turning my Father’s house into a marketplace!” (John 2:13-16)
If worshippers needed to buy animals and change money, why do you think Jesus reacted in this way?