Do you want it?

Jack stole the rabbi's gold watch and afterwards began to feel guilty about what he did. After a sleepless night, he went to see his rabbi.
"Rabbi, I stole a gold watch," Jack admitted sheepishly.
"But Jack, that's forbidden," replied the Rabbi. "You should return it immediately!"
"What shall I do?"
"Give it back to its owner," answered the Rabbi.
"Do you want it," asked Jack slyly.
"No, I said return it to its owner."
"But he doesn't want it," said Jack.
"In that case Jack," pronounced the Rabbi, "you can keep it."