In Numbers 15, God told the people to stone a man to death. What was his crime?

He gathered sticks on the Sabbath.

And while the children of Israel were in the wilderness, they found a man that gathered sticks upon the sabbath day.

And they that found him gathering sticks brought him unto Moses and Aaron, and unto all the congregation.

And they put him in ward, because it was not declared what should be done to him.

And the LORD said unto Moses, The man shall be surely put to death: all the congregation shall stone him with stones without the camp.

And all the congregation brought him without the camp, and stoned him with stones, and he died; as the LORD commanded Moses. Numbers 15:32-36