Matthew 26:17-20 "Now on the first day of Unleavened Bread the disciples came to Jesus and asked, “Where do You want us to prepare for You to eat the Passover?” 18 And He said, “Go into the city to a certain man, and say to him, ‘The Teacher says, “My time is near; I am to keep the Passover at your house with My disciples.”’” 19 The disciples did as Jesus had directed them; and they prepared the Passover.
20 Now when evening came, Jesus was reclining at the table with the twelve disciples."
Eventually, the Jews were commanded to travel far and wide to celebrate the Passover in Jerusalem. Preparation focused one's intention and will on bringing pleasure to their Lord. The external rites associated with Passover and the later New Covenant meal of the Lord's Supper were Divinely given to order the interior lives of God's people. To neglect preparation of one's heart and mind in the things of God can lead to a later inability to digest later truths God wants to impart through His word.