Jesus healed the sick man immediately and only asked him to obey. To prove that the man was healed, Jesus told him to pick up his mat and walk.
Jesus performed this miracle on the Sabbath. The Sabbath was a weekly day of rest. The law of Moses said that no work should be done on that day (based on Genesis 2:2; Exodus 20:8). Jewish tradition identified 39 types of work that were not allowed (Mishnah Shabbat 7:2). One rule said that a person could not carry an object, such as a sleeping mat, from one place to another (John 5:10).
Jesus told the healed man to pick up his mat and walk. When the man obeyed Jesus, he broke this later Jewish tradition.