on something from which he can benefit. Based on this, this issue may be posed as a riddle: What is something from which one may benefit, yet which one may not sell in order to buy something else to benefit from in its place?
The answer: if the one offering the sacrifice wishes to tan the hide and make it into a waterskin, that is permissible. But if he wishes to sell it and, instead of the waterskin, buy a water container such as a thermos flask, for example, that is not permissible. All of this is to safeguard what he has given for Allah’s sake from being taken back.
“If it develops a defect, he must slaughter it, and it suffices for him, unless it had already become binding upon him as a liability before designation.”
His statement, “If it develops a defect, he must slaughter it, and it suffices for him, unless it had already become binding upon him as a liability before designation”: the subject of “develops a defect” refers to the animal that has become designated, whether a sacrificial animal for pilgrimage or an udhiyah. This is one of the consequences of our saying that it becomes designated: if it develops a defect that prevents it from being valid, he must slaughter it, and it suffices for him.
For example, if he buys a sheep for an udhiyah, then, after designating it, its leg is broken and it becomes unable to walk alongside sound sheep, then in this case he must slaughter it, and it suffices for him. Once it was designated, it became a trust in his possession, like an item left in safekeeping. If it developed the defect neither through his transgression nor through his negligence, then he is not liable for it; rather, he slaughters it, and it suffices for him.
Perhaps evidence for this may be drawn from the story of the man who bought an udhiyah, and then a wolf attacked its fat tail and ate it, whereupon the Prophet, peace and blessings be upon him, permitted him to offer it as a sacrifice (1). This is because the loss of the fat tail is a defect that prevents validity; however, since this defect occurred after designation and was neither due to his negligence nor his own action, he was a trustee and bore no liability.