Targum zu Bamidbar 15:32

And while the sons of Israel were dwelling in the wilderness, the decree of the Sabbath was known to them, but the punishment (for the profanation) of the Sabbath was not known. And there arose a man of the house of Joseph, and said with himself: I will go and pull up wood on the Sabbath day; and witnesses saw it, and told Mosheh; and Mosheh sought instruction from the presence of the Lord, that he might teach me judgment, and make known the discipline of all the house of Israel. And the witnesses of the man who pulled up and collected wood came,

Stealing wood.