Is it permissible to make a vow to fast continuously until a desired matter is achieved, by saying: "I have vowed to Allah to fast until Allah fulfills my request"?

The conditional vow (nadhr mu'allaq) is disliked because the Prophet, peace and blessings be upon him, forbade it, for it does not avert anything from destiny; rather, it only extracts from the miser. Therefore, one should not vow to fast consecutively to fulfill a need, as it may be difficult or impossible to fulfill, leading to the person being blameworthy in the sight of Allah. The best approach for fulfilling a need is to increase supplication (du'a) and to draw closer to Allah through supererogatory fasting and good deeds.