Responsa for Bava Metzia 71:17

Q. A married off his son to B's daughter, giving a dowry of twenty marks which A deposited with B. Subsequently, A's son quarrelled with his wife and returned to his father's house. He appointed his father his trustee and the latter demanded that B return the dowry deposited with him since it was given to him for safe-keeping only. B claimed that he gave the money to his daughter while the young couple still lived happily together; that his daughter used the money in business since she was active in business and earned the income for the family, while her husband devoted all his time to studies; that A's son never asked him for the money, and that A never told him not to give the money to his daughter. B also mentioned his daughter's complaints that A's son did unmentionable things to her, conducting himself in a disgusting manner, and thus became hateful to her. She now demanded that he divorce her and pay her the ketubah, as she said that she despised her husband, would never live with him again, and would rather go begging from door to door than remain with him.
A. B must take an oath to the effect that he gave the money to his daughter while she was still living in peace and harmony with her husband, and thus be free from obligation. Since B's daughter was a rebellious wife she ought to be dealt with as such. I already wrote to you, while I was in Konstanze, my opinion regarding the law governing a rebellious wife. We follow the ordinance of the Geonim and permit her to keep all she brought to her husband as dowry (Nikse Zon Barzel), and whatever he brought is returned to him, nor is she entitled to the Ikkar ketubah; she is then to wait until either he consents to divorce her, or she decides to go back to him. If we suspect, however, that she does not dislike her husband but revolts against him because of financial considerations, or because her father, her mother, or her relatives induce her to quarrel with him, we take away from her even her dowry. In such a case we must follow the law in all its strictness and give all the possessions of the couple to the husband, for the ordinance of the Geonim mentioned above does not apply to the woman who rebels against her husband because she is persuaded to do so by others.
SOURCES: Cr. 93, 94; L. 327, 328; Mord. Ket. 186–7; cf. Mordecai Hagadol, p. 160d; Terumat Hadeshen 220; Isserlein, Pesakim 264.