Without an intention, the statement is not considered a vow
9-8-2015 | IslamWeb
Question:
My husband intended to slaughter a sheep after we bought our new car, and he intended to distribute its meat just like the ‘aqeeqah (slaughtering for a newborn) and udh-hiyah (slaughtering for eid al-adh-ha) are distributed; (a third for us, a third for relatives, and a third for poor people). He did that and then one of my friends told me that this is considered a vow and that the slaughtered sheep should completely have been given to the poor. However, my husband's intention was not to make a vow, yet it was merely to offer the sheep as a 'sacrifice' (fadw) for the new car so that Allah Almighty would bless it for us. What is the sharia ruling in this case?
Answer:
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 
is His slave and Messenger.
There is no doubt that when Allaah, the Exalted, confers a blessing upon a person, he should express his gratitude to Him for it. Spending in charity when the person is granted a blessing is considered a way of showing gratitude to Allaah, the Exalted.
However, confining the expression of gratitude to sacrificing an animal as is commonly known among many people is considered a religious innovation. This is because there is no religious text in the Quran, the Sunnah, or the practice of our righteous predecessors 
from which such restriction is deduced. This habit is usually accompanied by a false conviction on the part of those who observe it. They assume that if they do not offer a slaughtered animal as a sacrifice or ransom for themselves, their homes, children, mounts, and so on, a calamity will befall them (their homes, children, mounts, and so on). Indeed, this is groundless and has no basis in the Islamic Sharee'ah.
However, if your husband does not hold such a false and corrupted conviction and does not believe that expressing gratitude to Allaah, the Exalted, for a blessing is confined to offering an animal as a sacrifice and he just slaughtered the sheep as a means to draw closer to Allaah, the Exalted, then he will earn the rewards for his act. He may distribute the meat of the slaughtered sheep in the way that he wishes and in the manner that he prefers. It is not incumbent on him to give it all to the poor as long as he did not intend it as a vow to be given to them.
Allaah Knows best.