I have heard the phrase from both coaches and officials, "the hand is part of the ball".

1) Is this true?
2) Is there a reference in the rules and where?

I think that type of interpretation promotes bad defense.

4-24-2 says it's legal, in fact it uses the words TO REACH in this section.

How is attacking the ball bad defense?

To me good defense is moving feet, body positioning, and attacking the ball LEGALLY.

That is precisely my point. Normally slapping at the ball is done in lieu of a player defensively positioning his /her body between the offensive player and the basket. It usually occurrs when a defensive player has been beaten and I see no reason why the rules of basketball would want to reward a defensive player for lazy or inferior play.

I see players all the time attack the ball with good positioning. The matador move happens, but unless the dribbler is sloppy, or the defender has very long arms it is unlikely that you will have the hit on hand/ball, it's usually between the wrist and the elbow, at least that's where I see it. ;)

The rules <b>don't</b>. R4-24-2 says that it's legal to <b>accidentally</b> hit the hand that is contacting the ball. If you feel that the defender's whack on the hand is <b>deliberate</b> instead of accidental, the rules say that you can call it a foul. Your judgement. Personally, I don't think that I would ever be 100% sure that the defender's act was deliberate. I'm not a mind-reader.

Wouldn't it then be intentional? :D

Oh, yeah. Definitely. Please tell me when you're gonna make that call though. I wanna be as far away as possible. LOL!