Praise be to Allaah.
The dowry (mahr) is an obligatory part of the marriage
contract, as stipulated in the verse (interpretation of the meaning):
“All others are lawful,
provided you seek (them in marriage) with Mahr (bridal-money given by the
husband to his wife at the time of marriage) from your property, desiring
chastity, not committing illegal sexual intercourse, so with those of whom
you have enjoyed sexual relations, give them their Mahr as prescribed”
It is Sunnah to stipulate the dowry in the marriage contract,
but if it is not stipulated, the marriage is still valid and the wife should
be given a dowry like that of other women like her, who share the same
characteristics according to which the rates of dowries may differ.
The dowry should be known; if they agree to an unspecified
dowry, that is not valid, and the wife should be given a dowry like that of
Ibn Qudaamah (may Allaah have mercy on him) said: No dowry is
valid unless it is specified. This is the view of al-Shaafa’i. End quote
from al-Mughni, 7/168
It says in Ma’oonat Ooli al-Nuha (9/192): It is
essential that the dowry be known. Then he said: That applies to everything
of which the value is unknown and the way of obtaining it is unknown; it is
not valid as a dowry, and there is no difference of scholarly opinion on
this point. End quote.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said:
If he gives her something unknown as a dowry, that is not
permissible, and she should have a dowry like that of her peers. End quote
from al-Sharh al-Mumti’, 5/302
What is mentioned in the question about the uncle refusing to
stipulate a dowry and asking for the wedding expenses of his nephew to be
combined with those of his son, then shared equally, makes the dowry
unknown, because it is not known how much his son’s wedding expenses will
Based on this, this wife should be given a dowry like that of
other women who are like her, if the marriage contract has been done as you
describe. If the marriage contract has not yet been done, then a dowry
should be specified for her, and it is not permissible to do what your uncle
is asking, because that will lead to the dowry being unknown.
And Allaah knows best.