Is it obligatory to fulfill a vow not to benefit from the price of a land that the father bought with a usurious loan, knowing that benefiting from its price is not forbidden? And is it permissible or impermissible? And how does one repent from borrowing with usury?

"Specifying an oath by its cause is a matter of scholarly disagreement, as is whether a vow (nadhr) is to be treated similarly. Those who specify an oath by its cause and treat a vow similarly do not obligate fulfillment of the vow if its cause ceases to exist. Those who do not specify an oath by its cause, or do not treat a vow similarly, obligate its fulfillment absolutely. Some scholars are of the view that prioritizing the exact wording of the one making the vow is more sound, while others believe that prioritizing the intention and cause is more sound. However, in the case of a vow made to draw closer to Allah, its fulfillment is absolutely obligatory, even if the cause for which it was vowed ceases to exist, like the emigrants (Muhajireen) who were prevented from returning to Makkah after their emigration for Allah's sake. Based on this, the questioner must fulfill his vow and prohibit benefiting from the price of the land. As for repentance from a usurious loan, it is achieved through remorse, a firm resolve not to return to it, abandoning it, and returning the principal capital without any increase."