A man vowed to fast ten days at the beginning of a certain month but was unable to complete them all, so he postponed some of them to the second month

The questioner : He says: A man vowed to fast ten days at the beginning of a certain month but was unable to complete them all, so he postponed some of them to the second month. Is there an expiation upon him in this case?

The Shaykh : First, from this pulpit, the pulpit of "Light on the Path," we repeat the prohibition of vows, following the prohibition of the Prophet (peace and blessings be upon him) regarding them. Indeed, the Prophet (peace and blessings be upon him) prohibited vows and said: . And how many are the questioners who ask about vows they have made, either because they fall into distress and hope that if Allah saves them from it, they will give charity or fast, or because of a sick person they have, and they vow that if Allah heals him, they will give charity or fast, or because of the arrival of offspring, and they vow that if Allah grants them children, they will do such and such acts of worship, as if Allah (Mighty and Majestic) does not bestow His blessings upon them unless they condition this vow for Him.
And I, from this place, warn my Muslim brothers about vows and convey to them the prohibition of the Prophet (peace and blessings be upon him) regarding them, because they always vow and then regret it, and perhaps they vow and do not fulfill it. And what a great punishment is that of one who vows to Allah (Glorified and Exalted is He) and does not fulfill it. So let us listen to the saying of Allah the Exalted: .
Then, vows are of categories: some must be fulfilled, and some do not have to be fulfilled because they are in the nature of an oath. If a person vows an act of worship, whether it is an absolute vow or a conditional one, intending to perform that act of worship, it is obligatory for him to perform this act of worship.
An example of this is if a man says: "I owe Allah that I will pray two rak'ahs." This is an absolute vow of worship, so it is obligatory for him to pray immediately, unless he restricts it by time or place. If he restricts it by time, it is not obligatory for him to pray until that time comes. If he restricts it by place, he is not required to pray except in that place he vowed, unless there is a religious prohibition in it. However, it is permissible for him to pray it in another place, unless the place he specified has a special merit. In that case, it is not permissible for him to pray it in a place that does not have that merit. For example, if he vowed to pray in the Sacred Mosque, his prayer in other mosques does not suffice. If he vowed to pray in the Prophet's Mosque (peace and blessings be upon him), it suffices for him to pray in the Sacred Mosque instead. If he vowed it in Al-Aqsa Mosque, it suffices for him to pray in the Prophet's Mosque and the Sacred Mosque as well. If he vows the higher one, prayer in the lower one does not suffice. If he vows the lower one, prayer in the higher one suffices.
The important point is that a vow of worship must be fulfilled, whether it is absolute as we exemplified, or conditional, such as if he says: "If Allah heals my sick person, I owe Allah a vow to fast a month," or he says: "If I succeed in the exam, I owe Allah a vow to fast three days, or to fast on Monday and Thursday of such and such a month, or the like." It is obligatory for him to fulfill it due to the generality of the saying of the Prophet (peace and blessings be upon him): .
As for when the vow is in the nature of an oath, meaning he does not intend to worship Allah the Exalted with this specific act of worship, but the vow-maker intends to refrain from a specific action or to commit to a specific action, such as saying: "I owe Allah a vow not to wear this garment," then he has the choice between wearing it and paying the expiation for an oath. Or he says: "If I wear this garment, I owe Allah a vow to fast a month." Here, if he wears the garment, he is not required to fast a month. Rather, if he wishes, he fasts a month, and if he wishes, he expiates his vow with the expiation for an oath. Because every vow intended for prohibition, encouragement, affirmation, or denial is in the nature of an oath.
After this, we return to the answer to the question posed by the questioner, which is: he vowed to fast ten days of a certain month, then he did not fast them in that month and fasted them in the second month.
So we say to him: You have an expiation for an oath upon you, because your vow included two things:
It included fasting ten days and that they be in this specific month. So when it passed you that they be in this specific month, the expiation for an oath became obligatory upon you due to the loss of the attribute, as for the days, you have fasted them.
Finally, I hope from my Muslim brothers that they do not vow, that they do not burden themselves with these vows, that they do not oblige themselves with what Allah has not obligated upon them, that they do not do anything they will regret, and perhaps they will not fulfill it, and what befell those who covenanted with Allah will befall them: . I fear that if a person vows to Allah a vow like the one mentioned by Allah the Exalted and then does not fulfill it, Allah the Exalted will follow it with hypocrisy in his heart until death.
I hope and repeat my hope that my Muslim brothers pay attention to this issue, and that they stop from vows as their Prophet Muhammad (peace and blessings be upon him) prohibited them from them. And Allah is the Helper.