Long back I made a mannat that if so and so happens I will fast for so and so days. Like if my Aunty gets alright i will fast, if i pass in my exams i will fast, etc. But later on I came to know from someone that we should not make such mannat's. So I did not complete it. But now i feel that i should have completed it. I don't exactly remember for how many days had I made a mannat to fast. I am confused now. What to do?

All perfect praise be to Allaah, the Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

First of all, it is disliked to initiate a conditional vow, like when a person says: ‘If Allaah cures my patient or if I succeed in my exam I vow to Allaah to fast such and such number of days.” This vow is disliked as Ibn ‘Umar narrated that the Prophet forbade making such a vow as he said, “Making a vow does not bring any good but it only extracts from the stingy person.” [Al-Bukhari and Muslim] It means do not make a vow aiming to achieve something that was not predestined for you, or to repel something that was predestined for you. Rather, the person who makes a vow is stingy as he does not do this act of obedience voluntarily and wholeheartedly, but he does it in return for the cure of a patient or anything else on which he conditioned the vow. For more benefit, please refer to Fatwa 174679.

However, this does not mean that if one makes such a vow he is not required to fulfill it; rather, he is obliged to do so. It is for this reason that he said: "…it only extracts from a stingy person.” This means that it is an obligation to extract the vow from him, i.e. he is obliged to fulfill it; as the Prophet said: “Whoever has made a vow to obey Allaah, should obey Him." [Al-Bukhari and Muslim]

Therefore, you should fulfill the vow which you had made if the condition on which you had made the vow has been achieved. If you do not know the number of days which you vowed to fast, then you should estimate them and fast a number of days which you predominantly think you are required to fast.

For more benefit, please refer to Fataawa 83652, 86964 and 102811.

Allaah Knows best.