In B"M 30b a story is told of Rabbi Yishmael b"r Yosi who paid the owner of wood half a zuz to buy the wood rather than help him load it up. Although he was a zaken ve'enah lefi kevodo, this was lifnim mishuras hadin. He then was mafkir the wood, the former owner repossessed it, and RYB"Y paid him again. The third time the fellow tried to take the wood, and RYB"Y told him, shelo kehalacha, that it was hefker to all others but to him.
My question is, why did he pay him the second time rather than explain that he had no obligation to help him? Also, why did he think the man would stop at twice? Finally, by what right did he distort the halacha of hefker le'aniyim in order to not explain to the man what and why he was doing?
The Meforshim write that Rebbi Yishmael did not want to take advantage of the crown of Torah and therefore did not tell him that he was Patur. However, when actually one is Patur it seems that one may fool the other party.
D. Zupnik