Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: John was punching and punching at the wall but succeeded only in bloodying his knuckles. This was bad.  He would be unable to hold his tools if he injured what?
hands
his hand.