Husband asking his wife how she disposed of the mahr

It is not
permissible for a husband to question his wife about the mahr which he gave
to her, because this is her right and a debt on him which he has to give to
her. 

In return
for this small amount of money which Allaah has granted to the woman, the
right of qiwaamah (being in charge, being the protector and maintainer) is
taken from her and given to her husband. So his spending on her is in return
for something very precious and the mahr and spending on her is in return
for that qiwaamah. Allaah says (interpretation of the meaning): 

“Men are
the protectors and maintainers of women, because Allaah has made one of them
to excel the other, and because they spend (to support them) from their
means”

[al-Nisa’
4:34]

Imam
al-Tabari (may Allaah have mercy on him) said: 

“Men are the
ones who are in charge of their womenfolk, disciplining them and making them
fulfil their obligations towards Allaah and towards themselves. ‘Because
Allaah has made one of them to excel the other’ means, because Allaah
has given men an advantage over their wives because of the mahr which they
give to them, and because they spend on them from their own money, and they
take care of them. This is the way in which Allaah has caused them to excel
them. Hence they are in charge of them and women are expected to obey their
husbands. 

Tafseer
al-Tabari, 5/57 

So the mahr is the woman’s right, just
as qiwaamah is the man’s right. Just as she should not disobey him because
of that qiwaamah, so he should give her her rights. 

Men must
fear Allaah with regard to their wives’ mahr and give them their mahrs. For
women are weak, so men should give them their rights. 

Allaah says
(interpretation of the meaning): 

“O you
who believe! Fulfil (your) obligations”

[al-Maa’idah 5:1]

And indeed the marriage
contract is one of the most important contracts which the Muslims are
obliged to fulfil. 

It was
narrated that ‘Uqbah ibn ‘Aamir (may Allaah be pleased with him) said: The
Messenger of Allaah (peace and blessings of Allaah be upon him) said:
“The conditions which most deserve to be fulfilled are those by means of
which intimacy becomes permissible to you.”

(Narrated by
al-Bukhaari, 2520; Muslim, 2542) 

So long as a
woman has taken possession of this money in this manner, her husband has no
right to force her to spend it in a particular way, unless she is spending
it on something haraam, in which case he has the right to stop her from
spending it in haraam ways. 

Our advice to you is to deal with your husband gently and calmly when he questions you about the mahr, lest a dispute concerning this matter be the cause of letting the Shaytaan come between you, especially when you are at the beginning of your married life, which should be based on harmony and tolerance on both sides towards any shortcomings or transgressions on the other side.  We ask Allaah
to decree for you a happy life filled with obedience to Allaah and following his laws. And Allaah knows best.