If a person vows to offer a sacrifice for the poor, can he eat some of it?
Question

                More than a year ago, I vowed to offer a sacrifice to Allaah and to give some of this meat to my family, relatives and the poor. Now I have nearly enough money. Can I fulfil the vow during the days of Eid al-Adha? Is it permissible for me to give some of this meat to my immediate family? What are the conditions for this vow to be valid and acceptable?.
Praise be to Allah.Firstly: 
This vow 
    comes under the heading of vows to do acts of worship and obedience, so it 
    must be fulfilled, whether it was general or conditional. A general vow is 
    when a person says, for example, “I vow – or I promise to Allaah – that I 
    will sacrifice a sheep, or give it to the poor or to my relatives.” 
A 
    conditional vow is one where a person says, for example, “If Allaah heals 
    me, or if I succeed, or I get a salary, or I acquire such and such an amount 
    of money, I will offer a sacrifice etc.” 
With regard 
    to the obligation of fulfilling the vow, that is because the Prophet  
    (peace and blessings of Allaah be upon him) said: “Whoever vows to obey 
    Allaah, let him obey Him, but whoever vows to disobey Allaah, let him not 
    disobey Him.” Narrated by al-Bukhaari (6318). 
So long as 
    you did not stipulate a specific time for fulfilling your vow, then it is 
    permissible for you to fulfil it at any time, during the days of Eid al-Adha 
    or at any other time. 
But if you 
    intended to offer a sacrifice this year, the sacrifice in fulfilment of your 
    vow does not count as the udhiyah sacrifice too, even if it is sacrificed 
    during the days of Eid al-Adha. 
Secondly: 
If a person 
    vows to offer a sacrifice and give the meat to his family, relatives and the 
    poor, that includes his immediate family such as his wife and children, 
    because they are part of his family, unless he intended to exclude them, in 
    which case it should be done as he intended. 
As for the 
    one who made the vow, he is not entitled to eat from the sacrifice he vowed 
    to offer. If he does eat some, he must give the value of that to the poor. 
The fuqaha’ 
    (may Allaah have mercy on them) stated that he should not eat any of the 
    meat of the sacrifice that he vowed to offer. 

    See: Haashiyat Ibn ‘Aabideen (2/616) and al-Mughni (3/288). 
One of the 
    reasons that the fuqaha’ gave for the one who made the vow not being allowed 
    to eat any of the meat is that if you vowed to give it to the poor, for 
    example, then it is only for them, and you are not allowed to divert any of 
    it away from them. See al-Muntaqa by al-Baaji (2/318). 
In 
    al-Mawsoo’ah al-Fiqhiyyah (6/117) it says: With regard to a vow, it is 
    not permissible for the one who made the vow to eat any of the sacrifice 
    that he vowed to offer, because it is charity and it is not permissible to 
    eat from one's charity. This is in general, because there is a difference of 
    opinion with regard to a sacrifice that one has vowed to offer. Similarly 
    with regard to a general vow that one has not vowed to give specifically to 
    the poor – whether verbally or in one's intention – it is permissible to eat 
    from it according to the Maalikis and some of the Shaafa’is. End quote. 
And Allaah 
    knows best.