Gittin 45 - Giving one's sister a ring
If a man gives his sister a ring in marriage (which all know to be invalid), Rav says, he gave it for safekeeping to be returned, but Shmuel says, he gave it as a present to keep.
If a slave runs away to Israel, he is not returned to his master.
One should not ransom captives (with some exceptions) for much more than their worth. Is it not to burden the community, or not to accustom the captors to gain? - Unresolved.
One should not ransom tefillin or Torah for more than their worth nor should one provoke with low offer.