Muslims slaughter animals during `Eid in emulation of Prophet Abraham who was about to slaughter his son, Isma`eel (Ishmael), to show obedience to Almighty Allah, when Ishmael was redeemed by a ram brought to Abraham by Angel Gabriel. The Angel then conveyed to him Allah’s Command to slaughter the ram instead.
The late Sheikh Ibn `Uthaymeen, a prominent Saudi Muslim scholar (may Allah shower mercy on his soul), said: “If the sacrificial animal gets injured (develops a flaw), it may still be slaughtered, and this will suffice. An example of that is when a man buys a sheep to sacrifice it, then its leg is broken and it is unable to walk and keep up with the rest of the flock, after he has selected it for sacrifice. In this case it may be slaughtered, and this will suffice because when it was selected, it became a trust, like something that was entrusted to him. Because it is something entrusted and the injury was not the result of his action or his negligence, he is not obliged to offer any guarantee.”