What is the ruling of Sharia on someone who vowed to sacrifice a male sheep, but the butcher then slaughtered a pregnant female?

If a person agrees with a butcher to slaughter a "male lamb" but the butcher slaughters a female without their knowledge, the person has the option to reject it and demand a male lamb or a refund, or to accept the slaughtered ewe. This is based on the hadith: "Muslims are bound by their conditions."

Regarding the vow (nadhir), if someone vowed to slaughter a lamb (khroof) but instead slaughtered a sheep (shat min al-ghanam), if the sheep is superior (more meat or higher in price), then it is sufficient, because it is permissible to substitute a vowed item with something better. However, if the sheep is equal or lesser in value, it is not sufficient, especially since a male lamb is preferred.

In the case of slaughtering a pregnant ewe as a vow instead of a lamb, the pregnant ewe is not sufficient because it is neither better than nor equal to a lamb, and because pregnancy negatively affects the quantity and quality of its meat. Therefore, another lamb must be slaughtered to fulfill the vow.