Is it obligatory to give the father a portion of his daughter's mahr (dowry), knowing that he has abandoned her and does not provide for her, and he refuses her marriage except on this condition, which might affect her trousseau?

The daughter's maintenance is obligatory upon her father until she marries or becomes self-sufficient. Whoever spends on her can claim the maintenance back from the father, provided they were not donating it. The father's right to guardianship over his daughter is not forfeited by his refusal to spend, but a guardian does not have the right to prevent his ward from marrying a suitable person. It is not permissible for the father to condition his approval of his daughter's marriage on money being paid to him. Scholars have differed on the permissibility of a guardian stipulating a portion of his daughter's dowry for himself. If this is permissible, then what he stipulates becomes his right, provided it does not cause her injustice.