daf bit: Nedarim 33

[cellio]

The mishnah teaches: if a man has vowed not to benefit from his neighbor, the neighbor may still pay his shekel (temple tax), settle his debts (if the debtor does not otherwise benefit), or return a lost item to him. The gemara compares these acts to driving away a lion -- a neighborly act. (33a)

(Today is really daf 34, but the discussion there is pretty complicated, with no good entry points.)

Comments

[zevabe.livejournal.com]

"Benefit" in the MIshna generally means something along the lines of "gain some useful thing (thing including non-concrete things) from" Essentially you prohibit anything nice he might give you/do for you to yourself.