provide a replacement equal to it or better, because he has not fulfilled what is due from him. But if it had not been binding before designation, then we consider the matter: if he was negligent, he is liable; but if he was not negligent, then he bears no liability.
Another example: he buys a sacrificial animal for Hajj, then—after designating it—it escapes, he cannot catch it, and is unable to recover it. He must provide a replacement, because it was binding upon him as a liability before designation. As for a voluntary sacrificial animal for Hajj, he is not required to replace it.
If we say that he must provide a replacement, and he purchases and slaughters the replacement, then finds the stray animal that had escaped after slaughtering the replacement, must he slaughter it as well, or is the replacement sufficient?
The stronger view is that the replacement is sufficient, because the man became liable for what escaped and discharged his obligation by offering a replacement for it. If he may replace it with something better while it is still present, then this is even more appropriate when it has escaped. However, according to the madhhab, he may not reclaim the stray animal when he finds it; rather, he must slaughter it. They say: because this stray animal became designated through designation, so he is obligated to slaughter it. Yet this reasoning is weak. It did become designated by designation, but the replacement took its place, and thus his liability was discharged. If the animal that strayed then returns, it returns to the ownership of its owner, who may dispose of it as an owner disposes of his property.
Likewise, if a person vows to slaughter an udhiyah, then buys a sheep and says, “This is the udhiyah for my vow,” and it subsequently develops a defect through a broken limb, lameness, or something similar, then he must slaughter it because he designated it, and he must slaughter a replacement because it is not valid as a sacrifice. Thus, he must slaughter it and fulfill what became obligatory through the vow. The correct view, however, is contrary to this, as mentioned previously: if it develops a defect—even if it had been binding upon him as a liability before designation—he should slaughter a replacement that is equal to it or better, and that suffices. For Allah has not imposed two acts of worship upon His servants without cause.