I was watching a game using USFA rules.

A batter was hit by a pitch in the hands, which were on the bat.  The umpire said it was a hit by pitch and he rewarded the batter first base.

I have always thought that the hands were part of the bat and if you get hit in the hands, it counts as a foul ball.

Was the umpire correct in his call?
If you know the section of the rulebook that this is in, I would love to know!
Ive been reading, but can't find it.