Reported Speech

Firstly, you must know from an English stand point - "Can you pass me the magazine, please?" is kind of a request. Thus, both restructured sentences should work.

However, academically, the sentence 'Sally asked Paul whether he could pass her the magazine' should be better as the original sentence comprises a question mark or to put it simply, it is a question. Therefore the first sentence should be better, at least from a traditional point of view. The word 'whether' reflects just that.

it should be [Sally asked Paul whether he could pass her the magazine ]
because sally is asking someone to help.

I wounder i would help you=]