John 5:18

18 Because Jesus said this, the Jewish leaders became really angry. They wanted even more to kill him. Jesus not only worked on the day of rest. He was also calling God his own Father, so he was making himself equal with God.

5:16Jesus was obeying his Father, God. And God chose to make the man well on the Jewish day of rest. The man was not really working when he carried his mat. It was not a big heavy thing.