What is the ruling regarding a wife registering half of her house in her husband's name as a gift, then demanding it back in its entirety, claiming she did so under duress when she sought a divorce, and would the husband be sinful if he voluntarily returned ownership of the house to her?

Hadiths have forbidden a donor from revoking their gift, except for a father. Scholars have differed on whether a wife can revoke what she gifted to her husband. Some have forbidden her from revoking it, based on the general texts, while others have permitted her to revoke it. This is the view of Shuraih and Al-Zuhri, and one of the two sayings of Imam Ahmad. Imam Ahmad says that a wife might gift something to her husband out of fear of divorce or mistreatment. Others have taken a middle ground, permitting revocation if her intention was not merely the gift itself, but rather she had another intention such as improving marital relations, preventing harm, or avoiding divorce. If relations sour and she requests a divorce, or her husband divorces her, then it is among the noble virtues for the husband to return the gift to her.

If a wife gives her husband her gold or jewelry willingly, there is no harm in him taking it. If it was a loan, he must return it. If it was a gift, and the wife was shy about asking for it back, or feared his evil or divorce, then it is preferable for the husband to return it to her when he is able, out of noble virtues.