A vow is to make it obligatory on oneself to do something that is permissible in order to pay homage to Allâhu ta'âlâ. Another name for vow is nezir. It is acceptable and rewarding to make a vow to do something that is worship for the sake of Allâhu ta'âlâ. For example, "I pledge that I will fast tomorrow for the sake of Allâhu ta'âlâ!" or "I pledge that I will sacrifice a sacrifice for the sake of Allâhu ta'âlâ and distribute it to the poor!"
The sacrifice is an act of worship that must be performed after it has been offered. This is because the offerer has made a promise to Allah. Promises made to Allah must be fulfilled. In verse 270 of Surah Al-Baqarah, Allah says, "Allah is certainly aware of every expenditure you make and every sacrifice you make. Act accordingly and avoid injustice."
Conditions for sacrificing a sacrifice
The person offering the sacrifice must be Muslim, of puberty, of sound mind, and the sacrifice must not be an obligatory act of worship.
When is the sacrifice slaughtered?
Once the condition is fulfilled, the sacrifice should be slaughtered immediately. For example, if a person makes a vow saying, "If I have a child, I will slaughter the sacrifice," he should slaughter the sacrifice after the child is born. However, if the condition is fulfilled, but the sacrifice is not slaughtered, then the sacrifice must be made up. That is, it must be sacrificed at another time.
Meat of the sacrifice
The meat of the sacrifice cannot be eaten by the offerer, nor can his wife, father, mother, grandparents, children and grandchildren. He must give it as charity to the poor. If they have eaten it, they should give sadaqah equal to the value of what they ate.