A man came to a family to ask for a girl's hand in marriage. The girl's mother ended up marrying this man after an agreement was made that the man and the young girl were to marry. Is nikah between the man and the mother vaild?
no it is not valid
As-salamu alaikum, sister.
The answer to your question depends on circumstances that you have not made clear. Let me try and explain, taking the girl first:
You say that an ‘agreement’ was made that the man and the young girl ‘were to marry.’ Do you mean that nothing more was said than the equivalent of: ‘Yes that sounds like a great idea! Don’t see anything wrong with that. Let’s sort matters out.’?
If the answer is ‘yes’, then there was no binding agreement at all; leaving both parties free to go their separate ways.
For a marriage to be valid under Islamic law certain conditions have to be met:
There must be consent to the marriage (verbally and in writing), made by both the bride (with or without a male guardian - her Wali - depending on her personal circumstances. From what you have said the girl in question would have required a Wali, and this could be her father) and the groom. This is done through a formal proposal of marriage; and a formal acceptance of that proposal.
(Consent cannot be given by those who are not legally incapable of giving it, such a minors, or people to lack the mental capacity to understand and consent to a legal contract).
The bride has a right to receive a gift (more often called a dowry) from the groom. This is paid directly to her, and is her sole property as security in the marriage. It remains her sole property, even in case of later divorce. The gift (which may be of cash, property, or any other valuable asset) can be given in full, or by means of a payment schedule formally agreed at the time of contract signature. The gift may also be deferred until termination of the marriage through death or divorce; in which case any unpaid part of that gift becomes a debt against her husband’s estate.
Two adult witnesses are required to verify the marriage contract.
(There could well be Prenuptial Contract Conditions, but these conditions are optional, and their absence does not invalidate the marriage contract).
Once the contract has been signed, the couple are legally married from that moment, and enjoy all the rights and responsibilities of marriage .
(In some cultures the couple do not formally share a household until after a public wedding celebration has taken place).
If the man and the girl you speak of went through a formal process that included all of the above conditions then they became a married couple; in which case marriage with the bride’s mother is haram, since she and the groom would have become mahram to each other.
On the other hand, if a valid marriage did not take place between the man and the girl then that between the man and her mother could very well be valid, depending on the mother’s personal circumstances at the time of the marriage, and whether or not the required conditions were met.
Breaking an informal promise to marry might well be a sign of low character, but it is not a barrier to wedlock.
Between you and I (shhhhhhhh), the girl has had a very lucky escape (even though she doesn’t think so now). She deserves better! May Allah (Subḥānahu ūta'āla) bless her, and grant her true and lasting happiness with the right man; and for all of their lives togther.
I hope this helps.