“A verbal agreement is not a transfer of ownership. However, The halacha considers someone who makes an oral agreement and goes back on his word unfaithful and one who cannot be relied upon.
While a Beis Din (Court of Jewish law) cannot force one to uphold a verbal agreement, it views such a person as untrustworthy, and others should avoid doing business with him.
In previous times, when a Beis Din had more power, a person who did not keep his verbal agreement would be passul (disqualified) from being a witness in a Jewish court case or at a wedding.
A moral obligation is created when one makes a final verbal agreement with another (not during the negotiation process but once all the terms have been finalized).”