Will not fulfilling two vows made fifteen years ago, and providing for essential matters such as supporting family and purchasing a house through installments, affect the acceptance of prayers for my son's success in his studies? And does buying a house through an Islamic bank make it unlawful and prevent the acceptance of prayers?

The sister who asked the question must fulfill both of her vows, whether conditional or absolute. If the vow is an act of obedience to Allah Almighty, then it must be fulfilled, for the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him."

The vow must be fulfilled even if there was an intention to help the husband's family or buy a house, because the vow is an obligation and helping family is a voluntary act, and buying a house in installments does not contradict fulfilling the vow.

If the condition upon which the vow was contingent is not met, then fulfilling it is not obligatory.