Praise be to Allah, the Lord of Worlds.
Fulfilling a vow is an act of worship that brings a person closer to Allah. He the Almighty said,"…and pay their vows"{Al-Hajj, 29}. He the Exalted also praised those who fulfill their vows where He said, "(Because) they perform the vow and fear a day whereof the evil is wide-spreading,'{Al-Insan, 7}.
Whoever vowed to sacrifice a sheep or any other lawful animal, with specific conditions, then he is obliged to sacrifice that animal, be it young or old, clear of defects or not, and, in this case, it doesn`t have to meet the conditions stipulated in the animal offered as an Udhiyah.
If his vow was unconditional, then the majority of the scholars are of the view that he is obliged to sacrifice a sheep that meets the conditions stipulated in an Udhyah in terms of age and lack of defects. As for a sheep, it is conditioned that it passed one year of age or its teeth have fallen. As for a goat, it is conditioned that it completed two years of age and moved into the third. It is stated in {Moghni Al-Mohtajj, 3/331}, "If he vowed to sacrifice a camel, a cow or a sheep, then it must meet the conditions of an Udhyah, because sacrificing a baby camel, a calf or a baby sheep doesn`t avail him." However, Hanbali scholars have permitted sacrificing the six-month sheep, as indicated in Fatwa No. (3121).
Scholars have studied various vow utterances. Do they fall under the rulings of Sharia or custom? Tajud`deen Al-Subkhi said, "The famous rule amongst scholars is that whatever has no ruling in Sharia or language should be judged on basis of custom."{Al-Ibhaaj, 1/365}. If a person vowed to sacrifice an animal in general {without stating that it should meet certain conditions}, then there are two opinions: It either meets the conditions of an Udhyah or doesn`t.
It is stated in {Rawdat At-Talibeen, 3/331}, "About the considerable characteristics of the sacrifice offered in fulfilment of a vow: If the vow maker said, "It is a duty unto Allah for me to sacrifice a camel, a cow or a sheep," Should these animals meet the conditions of age and lack of defects stipulated in an Udhyah? There are two views in this regard: First, the vowed sacrifice meets the minimum requirement of its kind. Second, it meets the minimum requirement of drawing a person closer to Allah.
The first view is stronger." Whoever vowed to sacrifice an animal, but didn`t utter, in his vow, feeding its meat to the poor and haven`t intended doing so in the first place, some Shafie and Hanafie scholars are of the view that his vow is, in principle, invalid. It is stated in {Al-Majmou`, 8/469}, "The third: If he vowed to sacrifice an animal without specifying that it is offered as an Udhyah or else, for example, he said, it is a duty unto Allah for me to sacrifice this cow or camel. If he added: And give its meat to the poor or made that intention, then he is obliged to sacrifice that animal and give its meat to them.
However, if he didn`t say so, then there are two views: His vow is valid and he is obliged to sacrifice that animal and give its meat to the poor/charity.However, according to the most correct view, his vow is invalid, because when he made it he mentioned sacrificing the animal and not giving its meat to charity/poor. Therefore, that vow doesn`t get him closer to Allah, as it wasn`t meant for charity/poor in the first place." It is stated in {Ad-Dur Al-Mokhtar, 3/739}, "If he said, if I recover from my illness, I will sacrifice a sheep or a sheep is due on me, and he did recover, then he isn`t obliged to fulfil that vow…..Unless he said it is a duty unto Allah for me to sacrifice a sheep."
In conclusion, the conditioned vow must be fulfilled accordingly. Whereas, the unconditioned vow follows one of two opinions. First, the majority of the scholars are of the view that the vowed sacrifice should meet the conditions stipulated in an Udhyah in terms of age and defects. Second, some scholars permitted sacrificing the vowed animal, even if it didn`t meet the conditions stipulated in an Udhyah, and this is the stronger opinion of the Shafie scholars. Therefore, there is no blame in following the second opinion, but it is better to follow the first to be on the safe side as far as the teachings of Sharia are concerned. And Allah the Almighty knows best.