There is a common social custom that the mahr (dower), whether stated or not is relinquished by the bride. However I did so by my free will. My husband, in spite of that, gifted it to me. Can I use it?
Let me explain a few things. Religion has advised us to implement some of its commandments according to the prevailing social values. It is not necessary to follow the original practice. Mahr is a religious statute. It is a right of the wife and an obligation on the husband. If she relinquished her right, then it was her graciousness. If he still fulfilled it, then it was due of his chivalry. Now she may use it as she pleases.
This question was answered by Mr Ghamidi in Deen-o-Danish, an online TV session hosted by Dr Muneer Ahmad aired on Dunay TV. The text has been rendered into English by Mr Dhu al-Nurain.