Responsa על כתובות 191:1

Q - A married a widow L, who brought to A a dowry of valuables worth 500 (?). L had not taken the customary widows oath regarding her ketubah due from her former husband. L died, and the heirs from her former husband demand that A return the valuables to them.
A - Since L did not take an oath regarding her ketubah, A must return all the valuables which he received from L, to the heirs of her former husband.