*1 This is a generalization from two verses, as follows

-Ex23-04 Return the lost article of your PERSONAL ENEMY
-Dt22-01:03 Return the lost article of your PERSONAL FRIEND

So you return ANY article whether of your PERSONAL
ENEMY or your PERSONAL FRIEND--as you long as you
know the person PERSONALLY. The law however exempts
you from returning the article to a known thief (a
non PERSONAL enemy) who might be guessing the lost
objects signs*10

*10 Several points should be made here
FIRST POINT:
- Ex23-04 uses the word YOUR ENEMY
- Dt22-01:03 uses the word BROTHER 5 times
So the real generalization is from YOUR ENEMY & BROTHER

So everyone FROM your enemy TO your brother gets
articles returned. This would exclude people you
dont really know who might be guessing signs.

Jewish law goes into the subtlety of someone whom
you dont know either as your BROTHER or ENEMY.

2nd POINT: We mention Rashis literal language
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The verse says return the object AFTER YOUR BROTHER ASKS.
But no would return it before they are asked for it

So read the verse as follows; Return the objects
until you ASK ABOUT YOUR BROTHER--investigate him
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Thus it appears that Rashi is deriving the law
from a pun. (ASK ABOUT YOUR BROTHER vs YOUR
BROTHER ASKS) But the truth of the matter is that
Rashi is deriving the law from the generalization
and contrast of verses. Rashi as is his usual custom
expresses this technical derivation in a PUNchy
PUNny manner (so students will remember it).

3rd POINT
The main point in Rashi is that the two verses
have to be generalized. The details of how
this generalization takes place are subject to
Talmudic discussion. In this case the Talmud
and Rashi take an obvious approach of excluding
people (thiefs) who we would not expect the law
to cater to. But the main thrust of Rashi is
the generalization from two verses--the details
must be inferred.