It is Permissible for a Husband to Give His wife a Gift as He Wishes

Question :

A man wishes to present his wife with a gift from his property - whether it is a little or a lot - either money, property or gold. If he disposes of it in this way, does this harm his heirs who come after him? And what limits have been set by the Islamic Law for its disposal which must not be exceeded, is it a quarter or a third? And vice versa If the one giving the gift is a woman from her own private money, what is the limit that she may dispose of according to Islamic Law? Advise me and may Allah reward you with goodness.

Answer:

It is permissible for the husband to give his wife a gift while he is healthy and living, as he wishes, as a reward for her patience, or her good service, if he did not do so to the detriment of other heirs, and it is not restricted to a quarter of his property nor anything else. Similarly regarding the wife, it is permissible for her to give her husband whatever she wishes from her property or her dowry, according to the Words of Allah, Most High:
"But if they, of their own good pleasure, remit any part of it to you, take it, and enjoy it without fear of any harm (as Allah has made it lawful)."

But it is not permissible to do so if he is ill, because that is considered a bequest to an heir.

Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 5 Pages 51-52