A vow to sweep the mosque and pray in it, with doubt about fulfilling it

Question:
Honorable Shaykh! A woman vowed that if Allah cured her son, she would sweep the mosque and pray two rak'ahs in it. This was more than thirty years ago, and she is not certain whether she fulfilled her vow or not. What is required of her?

Answer:
Yes, this is a binding vow because a vow is an act of obedience. Sweeping the mosque, which is cleaning the mosque, is an act of obedience and worship. Therefore, if she vowed it, it is obligatory for her. Prayer is also an act of obedience and worship, so if she vowed it, it is obligatory for her. Thus, this vow is binding on her, and her obligation is not lifted unless she is certain that she has fulfilled the vow. As for the fact that she is hesitant or doubtful about whether she performed it or not, the default is that the obligation remains, because the default is that the obligation remains in her liability. She must seek to clear her liability of it. Yes.